//Index Terms  --   to be used in searches
// NUMBER PROPERTIES
// FACTORING
// FORMULAS
// EXPONENTIAL 
// SYSTEMS OF EQUATIONS AND INEQUALITIES 
// MATRICES
// SEQUENCES
// SETS 

var owl_caption = 
 '<img src="../../image/owl.gif" width="31" height="31" border="0" align="absmiddle">';
var owl_says = 
 '<span class = popup_text>When you see me, move your cursor over me.  I will give you helpful strategies and general procedures. <br>Sometimes moving your cursor over the arrows and equal symbols '
       +' will present explanations for the step. <br>Sometime my little apprentice, sitting next to me, will have information to '
       +'share with you. Anytime you see him touch him with your cursor.</span>';
var small_owl_caption = 
'<img src="../../image/icon_owl_small.gif" width="24" height="24" border="0" align="absmiddle">';
var small_owl_says = 
'<span class = popup_text>Hi, I may not yet be a wise old owl, but from time to time I will help explain.</span>';
var light_bulb =
 '<img src="../../image/light_bulb.gif" width="32" height="32" border="0" align="top" usemap="#Map_light_bulb40">'
var write_the_definition = 
	'<span class = popup_text>To write the definition means to write the definition exactly as presented on the website.</span>';

 //MISCELLANEOUS NOTATION ETC.
var summation_diagram =
'The parts of the summation symbol are explained in this diagram.<br><br>'
+'<img  class="graphicIndent" src="../../image_sequence/summation_diagram_small.gif" alt="Summation diagram" >';  


var summation_properties =
'<br><br>Rules for manipulating sums and the summation symbol are: <br><br>'
 +'<img class="graphicIndent" src="../../image_sequence/summation_properties_small.gif" alt="Summation properties" ><br>';
  
//INDEX_SEQUENCES
  var sequences_and_function_notation =
  'For most functions studied prior to this point in the course, function names have been '
 +'letters like f, g, h chosen from the middle of the alphabet and domain elements have '
 +'been letters like x, y, and z chosen from near the end of the alphabet.<br><br><br>'
 +'The names of generic sequences usually have names like a, b, c, and d chosen from the '
 +'beginning of the alphabet and domain elements are usually denoted by n to correspond with '
 +'and emphasize the fact that the domain of a sequence is the set of natural numbers.  '
 +'However, many special sequences have different names which have become standard '
 +'for those sequences. <br><br>' 
 +'Historical usage also suggests a slight variation in function notation as shown in the '
 +'following two diagrams.<br><br>'
 +'<img src="../../image_sequence/diagram_function_notation_small.gif" alt="normal function notation"> &nbsp; '
 +'<img src="../../image_sequence/diagram_sequence_function_notation_small.gif" alt="sequence function notation"><br><br>'
 +'The variation is to write the domain element as a subscript on the '
 +'function name rather than to enclose it in parenthesis.';
 

var terms_of_sequence =
  'When working with sequences, range elements are frequently called terms of the sequence.<br><br>'
 +'For example:<br>'
 +'  <ul>'
 +'    <li> The range element associated with the domain element 1 is called the first term of the sequence. </li>'
 +'    <li> The range element associated with the domain element 6 is called the sixth term of the sequence.</li>'
 +'    <li>The range element associated with the domain element n is called the n<sup>th</sup> term of the sequence. </li>'
 +'  </ul>'
 +'  <ul class = normal_text>'
 +'    <li>Because the domain of every sequence is <b>N</b>, the graph of a sequence will consist of a set of discrete points.</li>'
 +'    <li>Because the domain of every sequence is <b>N</b>, it is possible to speak of the first domain element.</li>'
 +'    <li>Because the domain of every sequence is <b>N</b>, it is possible to speak of the next domain element.</li>'
 +'    <li>Because the domain of every sequence is <b>N</b>, it is not possible to speak of the last domain element.</li>'
 +'    <li>Because the domain of every sequence is <b>N</b>, it is possible to ask about and compute the sum of the first k terms.  This is usually called the kth partial sum of the sequence.</li>'
 +'  </ul>'
+'<br>';




//INDEX_FORMULAS


var formula_meaning =
'In mathematics a <b class = "bold_blue">formula</b> (plural: formulae, formulæ or formulas) is a concise way of symbolically '
+'expressing a general relationship between quantities.  In beginning algebra courses that relationship is always '
+'expressed as an equation.  <br><br>Thus for the purpose of this course, <span class = highlight><b>a formula must be an equation</b></span>.';

 var formula_square_area =
 'The formula for the area of a '
 +'<span onMouseOver="return overlib(def_square,CAPTION, \'Definition of Square\')" onMouseOut="nd();"> <span class=popup_text_index>square</span></span>'
 +' with length x is <span class = "nobr">A = x<sup>2</sup></span>.';

 
 var formula_parallelogram_area =
 'The formula for the area of a '
 +'<span onMouseOver="return overlib(def_parallelogram,CAPTION, \'Definition of Parallelogram\')" onMouseOut="nd();"> <span class=popup_text_index>parallelogram</span></span>'
 +' with base x and height y is <span class = "nobr">A = xy</span>.';

 var formula_rectangle_area =
 'The formula for the area of a '
  +'<span onMouseOver="return overlib(def_rectangle,CAPTION, \'Definition of Rectangle\')" onMouseOut="nd();"> <span class=popup_text_index>rectangle</span></span>'
 +' with length x and width y is <span class = "nobr">A = xy</span>.'; 

 var formula_rectangle_perimeter =
 'The formula for the perimeter of a '
   +'<span onMouseOver="return overlib(def_rectangle,CAPTION, \'Definition of Rectangle\')" onMouseOut="nd();"> <span class=popup_text_index>rectangle</span></span>'
+' with length x and width y is <span class = "nobr">P = 2x + 2y</span>.';

 var formula_rectangular_solid_volume =
 'The formula for the volume of a rectangular solid of length a, width b, and height c is given by <span class = "nobr">V = abc.</span>';
 
  var formula_rectangular_solid_surface_area =
 'The formula for the surface area of a rectangular solid of length a, width b, and height c is given by <br><br>'
 +'<span class = "nobr">Surface Area = 2(ab) + 2(ac) + 2(bc).</span>';

 var formula_triangle_area =
 'The formula for the area of a '
   +'<span onMouseOver="return overlib(def_triangle,CAPTION, \'Definition of Triangle\')" onMouseOut="nd();"> <span class=popup_text_index>triangle</span></span>'
+' with base b and height h is <IMG src="../../image/formula_triangle_area_small.gif"  align=Absmiddle>.';

 var formula_trapezoid_area =
 'The formula for the area of a '
   +'<span onMouseOver="return overlib(def_trapezoid,CAPTION, \'Definition of Trapezoid\')" onMouseOut="nd();"> <span class=popup_text_index>trapezoid</span></span>'
+' with bases B and b and height h is <br><br><IMG src="../../image/formula_trapezoid_area_small.gif"  align=Absmiddle>.';

 var formula_circle_area =
 'The formula for the area of a '
   +'<span onMouseOver="return overlib(def_circle,CAPTION, \'Definition of Circle\')" onMouseOut="nd();"> <span class=popup_text_index>circle</span></span>'
+' with '
+'<span onMouseOver="return overlib(def_radius,CAPTION, \'Definition of Radius\')" onMouseOut="nd();"> <span class=popup_text_index>radius</span></span> '
+'r is: <img src="../../image/formula_circle_area_small.gif" alt="Area of a circle" border="0" align="absmiddle">.';


 var formula_circle_circumference =
 'The formula for the circumference of a '
    +'<span onMouseOver="return overlib(def_circle,CAPTION, \'Definition of Circle\')" onMouseOut="nd();"> <span class=popup_text_index>circle</span></span>'
+' with '
+'<span onMouseOver="return overlib(def_radius,CAPTION, \'Definition of Radius\')" onMouseOut="nd();"> <span class=popup_text_index>radius</span></span> '
+'r is: <IMG src="../../image/formula_circle_circumference_small.gif" alt="Circumference of a circle" border="0"  align=Absmiddle>.';

 var formula_sphere_surface_area =
 'The formula for the surface area of a sphere with radius r is '
+'<IMG src="../../image/formula_sphere_surface_area_small.gif" align=Absmiddle>.';

 var formula_sphere_volume =
 'The formula for the volume of a sphere with radius r is '
+'<IMG src="../../image/formula_sphere_volume_small.gif" align=Absmiddle>.';

 var formula_cylinder_volume =
 'The formula for the volume of a cylinder with radius r and height h is '
+'<IMG src="../../image/formula_cylinder_volume_small.gif" align=Absmiddle>.';

 var formula_cone_volume =
 'The formula for the volume of a cone with radius r and height h is '
+'<IMG src="../../image/formula_cone_volume_small.gif" align=Absmiddle>.';

 var formula_temperature_f_to_c =
 'To convert temperature measured in degrees Fahrenheit to degrees Celsius, use the formula:'
+'<IMG src="../../image/formula_temperature_F_to_C_small.gif" align=Absmiddle>';

 var formula_temperature_c_to_f =
 'To convert temperature measured in degrees Celsius to degrees Fahrenheit, use the formula:'
+'<IMG src="../../image/formula_temperature_C_to_F_small.gif" align=Absmiddle>.';

 var formula_temperature_c_to_k =
 'To convert temperature measured in degrees Celsius to degrees Kelvin, use the formula:'
+'<IMG src="../../image/formula_temperature_C_to_K_small.gif" align=Absmiddle>.';

 var formula_distance_between_points =
 'The distance d between two points <span class = "nobr">(x<sub>1</sub>, y<sub>1</sub>)</span> and <span class = "nobr">(x<sub>2</sub>, y<sub>2</sub>)</span> '
 +'is given by the formula:<br><br><br>'
 +'<span class = "formula"><img src="../../image/formula_distance_large.gif" alt="d equals the square root of paren x sub 1 minus x sub 2 paren squared plus paren y sub 1 minus y sub 2 paren squared">.</span>';
 
  var formula_midpoint_between_points =
 'The midpoint of the line segment joining two points <span class = "nobr">(x<sub>1</sub>, y<sub>1</sub>)</span> and <span class = "nobr">(x<sub>2</sub>, y<sub>2</sub>)</span> '
 +'is given by the formula:<br><br>'
 +'<span class = "formula"><img src="../../image/formula_midpoint_large.gif" align="absmiddle"></span>.';

 
 var formula_pythagorean_theorem =
 'If  a and b are the lengths of the legs of a right triangle with hypotenuse of length c, then <br><br>'
 +'<span class = "formula"><span class = "nobr">a<sup>2</sup> + b<sup>2</sup> = c<sup>2</sup>.</span></span>';
 
 var formula_percent =
 'Percentage = (Percent)(Base).  <br><br>If we call Percentage the Amount, the formula becomes '
+' <span class = "nobr">Amount = (Percent)(Base)</span> and if we then replace the words with single letters we obtain a very usable '
+'formula which relates percentage, percent, and base.<br><br> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'
+'<b class = bold_blue><span class = "nobr">A = PB.</span></b><br><br> which is read as <br>'
+' <b class = bold_blue>The percentage A is P percent of the base B.</b>';

 var percent_problems_three_kinds =
 'There are only three percent related problems:'
 +'<ol class = "decimal">'
 +'<li><b>Given Percent and Base, calculate Percentage</li>'
+'<li>Given Percent and Percentage, calculate Base</li>'
+'<li>Given Percentage and Base, calculate Percent</b></li>'
+'</ol>';

 var formula_distance_traveled =
 'The distance d traveled at a rate r in time t is given by <span class = "nobr">d = rt.</span>';

 var formula_simple_interest =
 'The interest I earned by a principle P at a rate r for a time t is  <span class = "nobr">I = Prt.</span>';
 
 
//END OF FORMULAS

var less_than_facts= 
'Another more precise and more algebraic definition of less than is that a is less than b if <span class = "nobr">b - a</span> is positive.<br><br>'
+'The expression  <span class = "nobr">a < b</span> means a is less than b.<br>'
+'The expression  <span class = "nobr">a < b</span> means a is to the left of b on the number line.<br>'
+'The expression  <span class = "nobr">a < b</span> means <span class = "nobr">b - a</span> is positive.';

var greater_than_facts=
'Another more precise and more algebraic definition of greater than is that a is greater than b if <span class = "nobr">a - b</span> is positive.<br><br>'
+'The expression  <span class = "nobr">a > b</span> means a is greater than b.<br>'
+'The expression  <span class = "nobr">a > b</span> means a is to the right of b on the number line.<br>'
+'The expression  <span class = "nobr">a > b</span> means <span class = "nobr">a - b</span> is positive.'

// SETS 
 var set_element_circular=
' Notice that the above two definitions are circular in nature.  That is, each uses the other.  Therefore, we have no absolute definition of set nor do we have an absolute definition of element of a set.  Every logical discussion must have at least one undefined term, and in our discussion we will leave set and element of a set as two undefined terms.  The above two definitions will be sufficient for an understanding of everything we will do with sets.';
 
var set_not_numbers = 
'Avoid thinking of sets as collections of numbers.  The elements of a set may be things like: people, books, numbers, matricies, functions, equations, rational numbers, desks, polynomials, polynomial equations, polynomial functions, candy bars, clouds, cars, buses, trains, states in the US, countries of the world, computers, geometric figures, essays, test scores, jokes, minerals, trees, flowers, etc.'; 
 
var set_mathematical_creatures =
'In this course most of the sets we will discuss will be sets of mathematical creatures (objects) but not necessarily numbers.  There are very many mathematical creatures other than numbers.';
 
var set_notation =
'It is common practice to use symbols to make mathematical discussions more precise and more concise.  Some of the symbols, notation and terminology used to discuss sets pervades all of mathematics.<br><br>'
+'It is conventional to use capital letters to name sets.  Some of these letters are reserved for special sets while others are defined only for the duration of a particular discussion.  For example <b>R</b> is reserved for the set of Real Numbers and <b>N</b> is reserved for the set of Natural Numbers.  These are conventions only, so the reservation is not absolute.  For example <b>Q</b> is reserved for the set of  Rational Numbers but <b>Q</b> is also used for other sets when there is no chance for confusion.<br>'
+'It is conventional to use lower case letters to name elements of a set.  This is a convention only and may be violated at times.';

var incorrect_use_of_set_symbols=
'If k is an element of a set K, it is meaningless to write k <img src="../../image/symbol_set_subset_proper_small.gif" alt="is a subset of" border="0" align="absmiddle"> K.<br><br>'
+'If k is an element of a set K, it is correct to write k <img src="../../image/symbol_set_isin_small.gif" alt="is an element of" border="0" align="absmiddle"> K.<br>'
+'If A is a subset of B, it is meaningless to write A <img src="../../image/symbol_set_isin_small.gif" alt="is an element of" border="0" align="absmiddle"> B.<br>'
+'If A is a subset of B, it is correct to write A <img src="../../image/symbol_set_subset_proper_small.gif" alt="is a subset of" border="0" align="absmiddle"> B.';

var empty_subset=
'The empty set <img src="../../image/symbol_set_null_small.gif" alt="the null set"> '
+'is a subset of every set.  Can you explain why this is true? <br><br>Note this implies that every set has at least one subset. You should wonder: '
+'How many subsets does a given set have?';
 
var subset_of_self=
'Every set is a subset of itself. Can you explain why this is true?<br><br>'
+'Note we now know that every set, except the empty set, has at least two subsets. '
+'Why is there an exception for the empty set?';
 
 
//END OF SETS 
 
//INDEX NUMBER PROPERTIES

var one_primality = 
'The natural number 1 is neither a prime number nor a composite number.';

var rational_decimal = 
'The decimal representation of a rational number  is a terminating or a repeating decimal.';

var irrational_example = 
'Numbers like pi, square root of 2, and the cube root of 5 are examples of irrational numbers.';

var irrational_not_rational = 
'A real number which is not rational is irrational.';

var rational_not_irrational = 
'A real number which is not irrational is rational.';

var irrational_decimal = 
'The decimal representation of an irrational number is neither terminating nor repeating.';

var subset_chain_real = 
'The following are important subset relationships between the various subsets of the Real Numbers.<br><br>'
+'<p class = "display_left"><img src="../../image/number_set_chain_reals_small.gif" alt="Chain of subsets of real numbers" border="0"></p>'
+'<p>Furthermore <img src="../../image/number_set_real_small.gif" alt="Reals equal intersection of rationals and irrations" border="0" align="absmiddle">'
+' and <img src="../../image/number_set_rational_intersect_irrational_small.gif" alt="Rationals intersect Irrationals is null set" border="0" align="absmiddle"> '
+' and <img src="../../image/number_set_irrational_subset_reals_small.gif" alt="Irrationals are a subset of the reals" border="0" align="absmiddle">'
+' and <img src="../../image/number_set_rational_subset_reals_small.gif" alt="Rationals are a subset of the reals" border="0" align="absmiddle">'
+'</p>';

var subset_chain_complex = 
'The following are important subset relationships between the various subsets of the Complex Numbers.<br><br>'
+'<p class = "display_left"><img src="../../image/number_set_chain_complex_small.gif" alt="Chain of subsets of complex numbers" border="0"></p>'
+'<p>Furthermore <img src="../../image/number_set_real_small.gif" alt="Reals equal intersection of rationals and irrations" border="0" align="absmiddle">'
+' and <img src="../../image/number_set_rational_intersect_irrational_small.gif" alt="Rationals intersect Irrationals is null set" border="0" align="absmiddle"> '
+' and <img src="../../image/number_set_irrational_subset_reals_small.gif" alt="Irrationals are a subset of the reals" border="0" align="absmiddle">'
+' and <img src="../../image/number_set_rational_subset_reals_small.gif" alt="Rationals are a subset of the reals" border="0" align="absmiddle">'
+'</p>';

var property_inheritance = 
'When a statement (property, rule, axiom, theorem) is made about the numbers in a particular set of numbers'
+' that property is true for all subsets of numbers contained in the set.';

var special_subsets = 
'<center><H2>Some special types of subsets of the Real Numbers:</H2>'
+'<p><img src="../../image/intervals.gif" alt="intervals" border="0" align="absmiddle"><br>'
+'<img src="../../image/rays.gif" alt="rays" border="0" align="absmiddle"></p></center>';

var subsets_of_numbers_venn1 = 
'<center><H3>A chart showing the relationship  between various sets of Complex Numbers .</H3></center>'
+' <p>If two sets are joined by lines the lower set is a subset of the uppermost set.</p>'
+'<p><center><img src="../../image/number_set_subset_relations_small.gif" alt="venn diagram of sets of complex numbers" border="0" align="absmiddle"></center></p>';


 var sign_of_product =
 'The product of two real numbers with the same signs is positive.<br><br>'
+'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The product of two real numbers with different '
+'signs is negative.'; 

 var sign_of_quotient =
 'The quotient of two real numbers with the same signs is positive.<br><br>'
+'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The quotient of two real numbers with different '
+'signs is negative.'; 
 
 var  division_of_zero =
 'The quotient of 0 divided by any non-zero real number is 0.<br>';

  
 var division_by_zero =
 'Division by zero is undefined.<br>';
 
 var order_of_operations =
 'If no grouping symbols are involved algebraic expressions MUST be evaluated using the following order:'
+'<ol class = "decimal">'
+'<li>Evaluate all exponential expressions </li>'
+'<li>Do all multiplications and divisions as they occur from left to right </li>'
+'<li>Do all additions and subtractions as they occur from left to right</li>'
+'</ol>'
+'<p>'
+'If grouping symbols are involved, remove the grouping symbols by evaluating the expressions inside each pair of grouping symbols '
+'using the following order:'
+'<ol class = "decimal">'
+'<li>Evaluate all exponential expressions '
+'</li>'
+'<li>Do all multiplications and divisions as they occur from left to right' 
+'</li>'
+'<li>Do all additions and subtractions as they occur from left to right </li>'
+'</ol>'
+'<p>When grouping symbols are nested, remove the innermost grouping symbols first -- '
+'work from the inside to the outside.';

 var transitive_property_of_inequality =
 'If a,  b, and c are real numbers such that <span class = "nobr">a < b</span> and <span class = "nobr">b < c</span>, then <span class = "nobr">a < c.</span>'; 
 
  var additive_property_of_inequality =
 'If a, b, c, and d are real numbers such that <span class = "nobr">a < b</span> and <span class = "nobr">c < d,</span> then <span class = "nobr">a + c < b + d.</span>'; 
 
  var multiplicative_property_of_inequality =
 'If a and b are real numbers such that <span class = "nobr">a < b</span> and c is a positive real number, then <span class = "nobr">ac < bc </span><br><br>'
 +'If a and b are real numbers such that <span class = "nobr">a < b</span> and c is a negative real number, then <span class = "nobr">ac > bc.</span>';

 var reflexive_property_of_equality =
 'If a is a real number, then <span class = "nobr">a = a.</span>'; 

 var symmetric_property_of_equality =
 'If a and b are real numbers and <span class = "nobr">a = b,</span> then <span class = "nobr">b = a.</span>'; 

 var transitive_property_of_equality =
 'If a, b, and c are real numbers such that <span class = "nobr">a = b</span> and <span class = "nobr">b = c,</span> then <span class = "nobr">a = c.</span>'; 

 var additive_property_of_equality =
 'If a, b, and c are real numbers and <span class = "nobr">a = b</span> , then <span class = "nobr">a + c = b + c.</span>'; 
 
 var multiplicative_property_of_equality =
 'If a, b, and c are real numbers and <span class = "nobr">a = b</span> , then <span class = "nobr">ac = bc.</span>'; 
 
 var distributive_property =
 'If a, b, and c are real numbers, then <span class = "nobr">a(b + c) = ab + ac.</span>'; 
 
 var commutative_property_of_addition =
 'If a and b are real numbers, then <span class = "nobr">a + b = b + a.</span>';  
 
 var commutative_property_of_multiplication =
 'If a and b are real numbers, then <span class = "nobr">ab = ba.</span>'; 
 
 var associative_property_of_addition =
 'If a, b, and c are real numbers, then <span class = "nobr">(a + b) + c = b + (a + c).</span>'; 
 
 var additive_identity =
 'If a is any real number, then <span class = "nobr">a + 0 = 0 + a = a.</span>  The number 0 is called the additive identity.';
 
 var multiplicative_identity =
 'If a is any real number, then <span class = "nobr">a(1) = (1)a = a.</span>  The number 1 is called the multiplicative identity.'; 
 
 var additive_inverse_existence =
'If a is any real number then its additive inverse -a exists and <span class = "nobr">a + (-a) = (-a) + a = 0.</span>'
+'<br><br>The additive inverse of a number is also called the opposite of the number.';

 var multiplicative_inverse_existence =
'If a is any real number, other than 0, then its multiplicative inverse 1/a exists and a <span class = "nobr">(1/a) = (1/a)a = 1.</span>'
+'<br><br>The multiplicative inverse of a number is also called the reciprocal of the number.';
 
  var associative_property_of_multiplication =
 'If a, b, and c are real numbers, then <span class = "nobr">(ab)c = b(ac).</span>';  
 
 var law_of_trichotomy =
 'If a and b are real numbers, then one and only one of the following is true:<br>'
 +'<ol class = "lroman">'
 +'<li><span class = "nobr">a < b</span></li>'
 +'<li><span class = "nobr">a = b</span></li>'
 +'<li><span class = "nobr">a > b</span></li>'   
 +'</ol>';
 var trichotomy_and_absolute_value =
 'As a result of the Law of Trichotomy there are exactly three possibilities when comparing the absolute value '
 +' of an expression with a number.'
 +'<ol class = "lroman">'
 +'<li><span class = "nobr">|expression| < k</span></li>'
 +'<li><span class = "nobr">|expression| = k</span></li>'
 +'<li><span class = "nobr">|expression| > k</span></li>' 
 +'</ol>';   
 
  var trichotomy_and_quadratic_functions =
 'Consider a quadratic function whose rule is written in the general form'
+' <span class = "nobr">f(x) = ax<sup>2</sup> + bx + c</span>.<br><br>  From the Law of Trichotomy '
+'it follows that exactly one of the following is true about the leading coefficient:'
 +'<ol>'
 +'<li><span class = "nobr">a < 0</span> and the parabola opens down.</li>'
 +'<li><span class = "nobr">a = 0</span> and the function is not quadratic.</li>'
 +'<li><span class = "nobr">a > 0</span> and the parabola opens up.</li>' 
 +'</ol>'
 +'Also from Law of Trichotomy '
+'it follows that exactly one of the following statements about the discriminant is true:'
 +'<ol>'
 +'<li><span class = "nobr">b<sup>2</sup> - 4ac < 0</span> and the parabola has no x-intercepts.</li>'
 +'<li><span class = "nobr">b<sup>2</sup> - 4ac  = 0</span> and the parabola has exactly one x-intercept.</li>'
 +'<li><span class = "nobr">b<sup>2</sup> - 4ac > 0</span> and the parabola has two x-intercepts.</li>' 
  +'</ol>'
  +'Pairing each of the two possibilities for the leading coefficient '
  +'with each of the three possibilities for the discriminant, we find the following six '
+' graphical configurations to be the only possibilities for the graph of a quadratic function.<br><br>'
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_1_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_2_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_3_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_4_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_5_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_6_small.gif" alt = "Graph of Quadratic Function">';  

 
  var trichotomy_and_quadratic_equation =
 'Consider a quadratic equation'
+' <span class = "nobr">y = ax<sup>2</sup> + bx + c</span>.<br><br>  From the Law of Trichotomy '
+'it follows that exactly one of the following is true about the leading coefficient:'
 +'<ol>'
 +'<li><span class = "nobr">a < 0</span> and the parabola opens down.</li>'
 +'<li><span class = "nobr">a = 0</span> and the function is not quadratic.</li>'
 +'<li><span class = "nobr">a > 0</span> and the parabola opens up.</li>' 
 +'</ol>'
 +'Also from Law of Trichotomy '
+'it follows that exactly one of the following statements about the discriminant is true:'
 +'<ol>'
 +'<li><span class = "nobr">b<sup>2</sup> - 4ac < 0</span> and the parabola has no x-intercepts.</li>'
 +'<li><span class = "nobr">b<sup>2</sup> - 4ac  = 0</span> and the parabola has exactly one x-intercept.</li>'
 +'<li><span class = "nobr">b<sup>2</sup> - 4ac > 0</span> and the parabola has two x-intercepts.</li>' 
  +'</ol>'
  +'Pairing each of the two possibilities for the leading coefficient '
  +'with each of the three possibilities for the discriminant, we find the following six '
+' graphical configurations to be the only possibilities for the graph of a quadratic equation in two variables.<br><br>'
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_1_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_2_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_3_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_4_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_5_small.gif" alt = "Graph of Quadratic Function"> '
+'<img class="display_graph" src="../../image/function_graphs/quadratic_function_graph_6_small.gif" alt = "Graph of Quadratic Function">';  



 var square_root_of_perfect_square =
 'The principal square root of a perfect square is a natural number.';

 var square_root_of_non_perfect_square =
 'The principal square root of a natural number which is not a perfect square is an irrational number.';
 //END OF NUMBER PROPERTIES
 
//INDEX_EXPONENTIAL 

var the_number_e =
'An important irrational number is named e. The first few digits in a '
 + 'decimal expression of e are given here: e &asymp;2.71828184590452<br><br><br>'
+'Other irrational numbers encountered earlier have had understandable explanations. '
+'It is easy to understand what is meant by the square root of 2. It may not be clear why '
+'it is irrational, but at least its meaning is clear. In the same way the number '
+'<img src="../../images_algebra/pi_large.gif" width="20" height="19" align="absmiddle"> is '
+'easily understood to be the ratio of the circumference of a circle divided by its '
+'diameter. The number e on the other hand has no simple explanation.';

 var exponential_function_fact1 =
 'For each exponential function, the y-intercept is 1.'; 
 var exponential_function_fact2 =
 'For each exponential function, there are no x-intercepts and thus no real zeros.'; 
 var exponential_function_fact3 =
 'For each exponential function, the graph is entirely above the x-axis.  That means '
 +'exp<sub>a</sub>(x)>0 for all real numbers x.';
 var exponential_function_fact4 =
 'For each exponential function, no horizontal line intersects the graph in more than one point.'
 +'That means each exp<sub>a</sub> passes the horizontal line test and therefore each exponential function '
 +'has an inverse.';
 var exponential_function_fact5 =
 'For each exponential function, the x-axis is a horizontal asymptote.';


 var logarithm_function_fact1 =
 'For each logarithm function, there is no y-intercept.'; 
 var logarithm_function_fact2 =
 'For each logarithm function, the x-intercept is 1. So each logarithm function has a real zero of 1. '; 
 var logarithm_function_fact3 =
 'For each logarithm function, the graph is entirely to the right of the y-axis.  That means '
 +'the domain of each logarithm function is the positive real numbers.';
 var logarithm_function_fact4 =
 'For each logarithm function, no horizontal line intersects the graph in more than one point.'
 +'That means each logarithm function passes the horizontal line test and therefore each logarithm function '
 +'has an inverse, namely the corresponding exponential function.';
 var logarithm_function_fact5 =
 'For each logarithm function, the y-axis is a vertical asymptote.';









var identification_of_real_and_complex_components=
'The complex component of a complex number written in standard form is the coefficient'
+'of the imaginary unit i.<br><br> The real component of a complex number written in'
+' standard form is the real number which is not the coefficient of i.';



 var fact_exponential_meaning =
 'When n is a natural number, the exponential expression a<sup>n</sup> is used to '
 +'indicate that the base a is multiplied times itself n times.'; 
 
 var fact_negative_base_even_exponent =
 'A negative number with an even exponent is a positive number.';  
 
 var fact_negative_base_odd_exponent =
 'A negative number with an odd exponent is a negative number.';   
 
 var fact_negative_sign_in_base =
 'If the base of an exponential includes a minus sign, such as -5 or -x, then that base MUST be enclosed '
 +'in parenthesis.<br><br>For example, if -5 is to be raised to the third power it must be written as <span class = "nobr">(-5)<sup>3</sup></span>';  

var exponent_product_of =
 'If m, n and a are real numbers then '
 +'<span class = "nobr">a<sup>m</sup>a<sup>n</sup> = a<sup>m + n</sup></span>.';

var exponent_quotient_of =
 'If m, n and a are real numbers then '
 +'<img src="../../image/exponent_quotient_of_small.gif" align=Absmiddle>.';

var zero_exponent =
 'If a is not zero then '
 +'<span class = "nobr">a<sup>0</sup> = 1</span>.';
 
var negative_one_exponent =
 'If a is not zero then '
 +'<img src="../../image/exponent_negative_one_small.gif" align=Absmiddle>.'; 

var negative_exponent =
 'If a is not zero and n is a real number then '
 +'<img src="../../image/exponent_negative_n_small.gif" align=Absmiddle>.'; 

var exponent_of_product =
 'If a, b and m are real numbers then '
 +'<span class = "nobr">(ab)<sup>m</sup> = a<sup>m</sup>b<sup>m</sup>.</span>'; 
 
 var exponent_of_quotient =
 'If a, b and m are real numbers then  '
 +'<img src="../../image/exponent_of_quotient_small.gif" align=Absmiddle>.'; 
 
 var exponent_of_exponential =
'If a, m and n are real numbers then '
 +'<span class = "nobr">(a<sup>m</sup>)<sup>n</sup> = a<sup>mn</sup>.</span>'; 

 var fact_fraction_three_signs_keyword =
 '<font color="#0000FF" size="5" face="Arial, Helvetica, sans-serif"><br><br>'
 +'<b><center>Three Signs of a Fraction</center></b></font>'; 
 var fact_fraction_three_signs_caption =
 '<center><b><font color= "#ffff00" size = "2">Definition</font></b></center><br>Three Signs of a Fraction'; 
 var fact_fraction_three_signs =
 'The sign of the fraction, the sign of the numerator, and the sign of the denominator produce four equivalent forms '
 +'of every fraction.<br><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'
 +'<IMG src="../../image/fraction_four_forms_small.gif" align=Absmiddle>'; 
 
var one_as_fraction =
 'If c represents a non-zero real number then '
 +'<IMG src="../../image/one_as_fraction.gif" align=Absmiddle> '; 

var improper_fraction_to_mixed_number =
 'To convert an improper fraction to a mixed number, divide the numerator by the denominator.  '
 +'The quotient is the whole number part of the mixed number and the remainder is the numerator of the '
 +'fractional part of the mixed number.'; 

var mixed_number_to_improper_fraction =
 'To convert a mixed number to an improper fraction, write the whole number as a '
 +'fraction and perform the indicated addition.'; 
 
var mixed_number_arithmetic =
 'If a mixed number is involved in any addition, subtraction, multiplication or division, change that mixed number '
 +'to an improper fraction before proceeding.';  

var fundamental_property_of_fractions =
 'If a represents a real number and b and c represent non-zero real numbers then '
 +'<IMG src="../../image/fraction_fundamental_property_small.gif" align=Absmiddle> ';
 
var fundamental_property_of_fractions_fact = 
 'The Fundamental Property of Fractions is as valid for rational expressions as it is for common fractions. The only '
+ 'difference is that when applying the property to rational expressions one must interpret a, b and c as polynomials.';
 
var product_of_fractions =
'If a, b, c, and d represent real numbers and b is not 0 and d is not 0 then '
+' <IMG src="../../image/product_of_fractions.gif"  align=Absmiddle> ';
 
var product_of_fractions_fact = 
 'The Rule for Multiplying Fractions is as valid for rational expressions as it is for common fractions. The only '
+'difference is that when applying the rule to rational expressions one must interpret a, b,c and d as polynomials.'; 
 
var product_of_fractions_remembering =
 'A good way to remember this rule is to observe that it states: <br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The numerator of a product is the product of the numerators and <br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The denominator of a product is the product of the denominators.';
 
var product_of_fractions_alert =
 'There is no requirement to find and/or use common denominators when multiplying fractions.';  
 
var quotient_of_fractions =
 'If a represents a real number and b, c, and d represent non-zero real numbers, then  '
 +'<IMG src="../../image/division_of_fractions_a.gif" width=192 height=47 align=Absmiddle> '; 
 
var quotient_of_fractions_fact =
'The definition of division as applied to fractions is as valid for rational expressions as it is for '
+'common fractions. The only difference is that when applying the rule to rational expressions one must '
+'interpret a, b,c and d as polynomials.';

var quotient_of_fractions_diagram =
'An alternate depiction of this definition of division whether applied to fractions or rational expressions is '
+'this familiar diagram  <br><br>'
+'<CENTER><IMG src="../../image/division_of_fractions.gif" width=327 height=271 align=Absmiddle></CENTER>';
 
var sum_of_fractions =
'If a, b, and d represent real numbers and d is not 0 then '
+' <IMG src="../../image/sum_of_fractions_a.gif"  align=Absmiddle> ';

var sum_of_fractions_two =
'If a, b, c, and d represent real numbers and neither b nor d is 0 then '
+'the sum <IMG src="../../image/sum_of_fractions_b_small.gif"  align=Absmiddle> is computed by '
+'reducing or expanding the two fractions to fractions with the same denominator and then adding those two '
+'fractions with the same denominator as described above.';

var sum_of_fractions_two_fact =
'Adding fractions with the different denominators is as valid for rational expressions as it is for common fractions. '
+'The only difference is that when applying the rule to rational expressions one must interpret a, b, c, and d as '
+'polynomials. ';

var difference_of_fractions =
 'Subtraction of fractions is defined as an addition as shown here. '
 +'<CENTER><IMG src="../../image/subtraction_of_fractions.gif"  align=Absmiddle></CENTER> '; 

var difference_of_fractions_process =
 'To subtract one fraction or rational expression from another, change the problem to an addition problem and '
 +'proceed according to the rules for addition.'; 
 
var expanding_fraction =
 'To expand a fraction choose a fraction with equal numerator and denominator such '
+'that the product of its denominator and the denominator we are expanding is the desired new '
+'denominator. The product of this newly created fraction and the original fraction is the '
+'desired expanded fraction.';



var sum_of_fractions_fact =
'The definition of addition as applied to fractions is as valid for rational expressions as it is for '
+'common fractions. The only difference is that when applying the rule to rational expressions one must '
+'interpret a, b,and d as polynomials.';

var sum_of_fractions_remembering =
 'A good way to remember this rule is to observe that it states: <br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The numerator of a sum is the sum of the numerators and <br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The denominator of a sum is the common denominator.';
 
var simplify_complex_fraction =
 'To simplify a complex fraction simply perform the indicated division.'; 
 
var simplify_complex_fraction_with_sums =
 'If any of the numerators or denominators of the fractions contain a sum or difference, the indicated addition '
 +'(or subtraction) should be performed before attempting the division.'; 
 
var simplify_complex_fractions_fact =
'Simplifying complex fractions is as valid for rational expressions as it is for '
+'common fractions. The only difference is that when applying the rule to rational expressions one must '
+'interpret numerators and denominators as polynomials.'; 
 
var simplify_complex_fractions_alternate =
'An alternate process for simplifying rational expressions is to multiply both the numerator and denominator  '
+'by the LCD of the rational expressions contained in the numerator AND the denominator. '; 
 
 

var adding_like_terms =
 'To add like terms, add their coefficients and keep the same variables with the same exponents.<br><br>'
+ 'Adding like terms is frequently called combining like terms.<br>'
+'Adding like terms is a direct application of the Distributive Property.';



var equation_circle =
 'The equation of a circle with radius r and center at the origin is <br><br><span class = "formula">x<sup>2</sup> + y<sup>2</sup> = r<sup>2</sup></span><br>'
 +'while the equation of a circle with radius r and center at the  point (h, k) is<br><span class = "formula">(x - h)<sup>2</sup> + (y - k)<sup>2</sup>= r<sup>2</sup>.</span><br>'
 +'The latter equation is called the <b class = "bold_blue">Standard Form</b> for the equation of a circle.<br><br>'
 +'If the Standard Form for the equation of a circle is expanded, '
 +'<b class = "bold_blue">The General Form</b> of the equation of a circle <br><span class = "nobr"><span class = "formula">x<sup>2</sup> + y<sup>2</sup> + Dx + Ey + F = 0 </span></span><br>'
 +'is obtained.';

var general_quadratic_two_variables_circle =
 'The <b class = "bold_blue">General Quadratic Equation</b> in two variables <br><br><span class = "nobr"><span class = "formula">Ax<sup>2</sup> + Bxy + Cy<sup>2</sup> + Dx + Ey + F = 0 </span></span><br>'
 +'is the equation of a circle if and only if A = C and B = 0.';

var general_form_to_standard_form =
 'The following process may be used to convert the General Form to the Standard Form so that the center and radius of the circle are obvious.<br><br>'
 +'<ol>'
	+'<li>Write an equivalent equation with variable terms on the left side and constants on the right side.</li>'
	+'<li>Complete the square on the x-terms and create an equation equivalent to the original by adding the same constant to the right side of the equation. </li>'
	+'<li>Complete the square on the y-terms and create an equation equivalent to the original by adding the same constant to the right side of the equation. </li>'
	+'<li>Factor both perfect square trinomials to arrive at the Standard Form.</li>'
 +'</ol>'
 +' The center and radius are now easily observed.'; 
 
 
 var pick_circle_origin=
   'Since the center is the origin (0,0) we use the equation <br>x<sup>2</sup> + y<sup>2</sup> = r<sup>2</sup>.'; 
   
 var find_radius_pick_circle_general=
   'Since the center is not the origin we use the equation <br>(x - h)<sup>2</sup> + (y - k)<sup>2</sup>= r<sup>2</sup>.  '
   +'However, before we can use that equation we must find the radius.   The radius is the distance from the center to '
   +' a point on the circle. We find the radius by using the distance formula to calculate the distance between<br> (3, -2) and (-1, 1).<br><br>'
   +' Recall the distance formula is: <IMG src="../../image/formula_distance.gif" width=188 height=28 align=Absmiddle>' ;    

 var pick_circle_general=
   'Since the center is not the origin we use the equation <br>(x - h)<sup>2</sup> + (y - k)<sup>2</sup>= r<sup>2</sup>.';    


var testing_a_point =
 'A point satisfies an equation if a true statement results when the coordinates of the point are substituted into the equation.<br>'
 +'If a true statement results, the point is on the graph of the equation.<br>'
 +'If a false statement results, the point is not on the graph of the equation.';
 
 var testing_a_solution =
 'Substitute the number into the equation.<br><br>'
 +'If a true statement results, the number is a solution of the equation.<br><br>'
 +'If a false statement results, the number is not a solution of the equation.';
 
 var finding_x_intercept =
 'The <span class=nobr>x-intecept</span> of the graph of an equation is found by setting <span class=nobr>y = 0</span> in the equation and solving for x.<br><br>'
 +'This works because every point on the <span class=nobr>x-axis</span> has 0 as its <span class=nobr>y-coordinate.</span>';

 
 var finding_y_intercept =
 'The <span class=nobr>y-intecept</span> of the graph of an equation is found by setting <span class=nobr>x = 0</span> in the equation and solving for y.<br><br>'
 +'This works because every point on the <span class=nobr>y-axis</span> has 0 as its <span class=nobr>x-coordinate.</span>';
 
  var generating_equivalent_equations1 =
 '<span class="highlight">If any expression is added to both sides of an equation the resulting equation '
 +'is equivalent to the original equation.</span>';
 
   var generating_equivalent_equations2 =
 '<span class="highlight">If both sides of an equation are multiplied by the same <span class=nobr>non-zero</span> real number, the resulting equation '
 +'is equivalent to the original equation.</span>'; 
 
    var generating_equivalent_equations1and2 =
 '<b class = "bigred" >Important Property 1:</b><span class="highlight">If any expression is added to both sides of an equation the resulting equation '
 +'is equivalent to the original equation.</span><br><br><br>'
 +'<b class = "bigred" >Important Property 2:</b><span class="highlight">If both sides of an equation are multiplied by the same non-zero real number, the resulting equation '
 +'is equivalent to the original equation.</span>'; 
 
 
   var linear_equation_one_variable_solving =
 '<span class = highlight><b>The process to solve a linear equation in one variable is to generate a sequence of equations each '
 +'equivalent to the previous equation until a simplest equation is obtained.</b></span>';  
 
 var number_of_solutions_linear_equation_one_variable =
 'A linear equation in one variable will have no solutions, one solution, or have all real numbers as solutions.'
 
 var comment_about_solving_linear_equations =
 'Start with the original equation (the one to be solved) and use the above two properties of equations to generate simpler '
 +'equations, all equivalent to the original equation, until a simplest equation is obtained.<br><br><br>'
 +'Recall that equivalent equations have the same solution set. Therefore the simplest equation found by the '
 +'above process has the same solution set as the original equation. The solution set for the simplest equation '
 +'is clearly the single number on one side of the equation. <br><br>'
 +'If the equation is not well formed, it is advisable to simplify the expression on each side of the equality '
 +'symbol before beginning to use the above two properties.  Adhere to the order of operations when simplifying '
 +'each side.';
 
 var linear_equation_one_variable_graph =
 'The '
 +'<span onMouseOver="return overlib(def_solution_set,CAPTION, \'Definition of Square\')" onMouseOut="nd();"> <span class=popup_text_index>solution set</span></span>'
 +' for conditional linear equation in one variable is a set containing a single number. '
 +'The '
 +'<span onMouseOver="return overlib(def_graph_of_equation,CAPTION, \'Definition of Graph of an Equation\')" onMouseOut="nd();"> <span class=popup_text_index>graph</span></span>'
 +' of a conditional linear equation in one variable is a single point on the Real Number Line.'
 +'<p>The solution set for a linear '
 +'<span onMouseOver="return overlib(def_contradiction,CAPTION, \'Definition of Contradiction\')" onMouseOut="nd();"> <span class=popup_text_index> contradiction</span></span>'
 +' in one variable is the empty set. A linear contradiction in one variable has no graph.</p>'
 +'<p>The solution set for a linear '
 +'<span onMouseOver="return overlib(def_identity,CAPTION, \'Definition of Identity\')" onMouseOut="nd();"> <span class=popup_text_index> identity</span></span>'
 +' in one variable is all Real Numbers. The graph of '
 +'a linear identity in one variable is the entire Real Number Line.</p> ';
 
 var linear_inequality_one_variable_graph =
 'The graph of  a linear inequality in one variable is the empty set, a ray, or the Real '
 +'Number Line.';   
 
  var linear_inequality_two_variable_graph =
 '<span class = popup_text>The graph of  a linear inequality in two variables is a half-plane bounded by the graph '
 +'of the corresponding boundary equation.</span>';   
 
 var square_root_of_both_sides =
 'If one takes the square root of both sides of an equation the resulting equations need not be '
 +'equivalent to the original equation.  However, the solution set of the resulting equation contains the '
 +'solution set of the original equation but it may also contain numbers which are not solutions of the'
 +' original equation.<br><br>  An important part of the solving process in this case involves substituing '
 +'the possible solutions into the original equation to determine which numbers are actually solutions.';
 
  var multiply_both_sides_by_variable1 =
 'When both sides of an equation are multiplied by an expression which contains a varible, the resulting equation '
 +'is generally NOT equivalent to the original equation.'; 
  
  var multiply_both_sides_by_variable2 =
 'When both sides of an equation are multiplied by an expression which contains a varible, the solution set of the '
 +'resulting equation CONTAINS the solution set of the original equation.';

 var domain_of_rational_expression =
 'The domain of a rational expression, unless otherwise stipulated, '
 +'is the set of all real numbers for which the denominator is not zero.';

  var solve_a_rational_equation =
 'To solve a rational equation; <br><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; '
 +'1) Multiply both sides of the equation by the LCD of all rational expressions in the equation.'
 +'<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  '
 +'2) Solve the resulting equation to obtain possible solutions of the original equation.'
 +'<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  '
 +'3) Determine the solution set of the original equation by checking each of the possible '
 +'solutions in the original equation.' ; 
 
  var solve_a_rational_equation_fact1 =
 'If both sides of a rational equation are multiplied by the LCD of the rational expressions in the equation '
 +'and if that LCD is a number (no variables), then the resulting equation is equivalent to the original equation.';

  var solve_a_rational_equation_fact2 =
 'The only way a possible rational solution (as found by the above process) can fail to be a solution of the original '
 +'equation is for the possible solution to cause a denominator in the original equation to be zero .  Consequently, '
 +'possible solutions can be checked by simply insuring that they do not cause any denominator to be zero. '; 
 
  var solve_a_rational_equation2 =
 'To solve a rational equation; <br><br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; '
 +'1) Add or subtract appropriate rational expressions to both sides of the equation to obtain 0 on one side of the equation.'
 +'<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  '
 +'2) Perform all the indicated additions and subtractions of rational expressions.'
 +'<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  '
 +'3) Use the Zero Factor Property to conclude the numerator must be zero.'
 +'<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  '
 +'4) Solve the resulting equation to obtain possible solutions of the original equation.'
 +'<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  '
 +'5) Determine the solution set of the original equation by checking each of the possible '
 +'solutions in the original equation.' ; 
 
  var compound_inequality_solution_intersection = 
  'The solution set of a compound inequality formed with the word <b class = "bold_blue">and</b> is the intersection of '
  +'the solution sets of the two inequalities.';
  
  
 var compound_inequality_solution_union = 
  'The solution set of a compound inequality formed with the word <b class = "bold_blue">or</b> is the union of '
  +'the solution sets of the two inequalities.';

 var compound_inequality_compact_notation =
 'When using the compact form of a compound inequality such as <span class = "nobr">a &lt; x &lt; b,</span> '
+'be careful to write only meaningful statements. The inequalities must both &quot;point&quot; '
+'in the same direction. The end expressions must be related as indicated by the inequality symbols. '
+'For example, in <span class = "nobr">a &lt; x &lt; b,</span> it must be true that <span class = "nobr">a '
+'&lt; b.</span>';

 var compound_inequality_absolute_value1 =
 ' If k is a positive number and X is either a single variable or a variable expression, then the inequality <br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'
 +'<span class = "nobr">| X | &lt; k</span>&nbsp;&nbsp; is equivalent '
 +'to&nbsp;&nbsp; <span class = "nobr">- k &lt; X &lt; k</span><br>';
 
 
  var compound_inequality_absolute_value2 =
 ' If k is a positive number and X is either a single variable or a variable expression, then the inequality <br><br>'
 +' &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'
+' <span class = "nobr">| X | &gt; k </span>&nbsp;&nbsp;is equivalent to &nbsp;&nbsp;<span class = "nobr">X &lt; - k OR X &gt; k </span><br>'
 +'Note this is a compound inequality formed with the word OR. <br>'
 +'Therefore the solution set is the union of the solution sets of the two individual inequalities.'; 
 
   var generating_equivalent_inequalities1 =
  '<span class = popup_text>If any expression is added to both sides of an inequality the resulting inequality '
 +'is equivalent to the original inequality.</span>';
 
   var generating_equivalent_inequalities2 =
 '<span class = popup_text>If both sides of an inequality are multiplied by the same positive real number, the resulting inequality '
 +'is equivalent to the original inequality.</span>';
 
   var generating_equivalent_inequalities3 =
 '<span class = popup_text>If both sides of an inequality are multiplied by the same negative real number and the inequality symbol is reversed, '
 +'the resulting inequality is equivalent to the original inequality.</span>';   

  var generating_equivalent_inequalities1and2and3=
  '<b class = "bigred" >Important Property 1:</b>If any expression is added to both sides of an inequality the resulting inequality '
 +'is equivalent to the original inequality.<br><br>'
 +'<b class = "bigred" >Important Property 2:</b>If both sides of an inequality are multiplied by the same positive real number, the resulting inequality '
 +'is equivalent to the original inequality.<br>'
 +'<b class = "bigred" >Important Property 3:</b>If both sides of an inequality are multiplied by the same negative real number and the inequality symbol is reversed, '
 +'the resulting inequality is equivalent to the original inequality.';

  var solving_inequality_in_one_variable =
  'Start with the original inequality (the one to be solved) and use the above three properties to generate '
  +'simpler inequalities, all equivalent to the original inequality, until a simplest inequality is obtained.  ';

var linear_inequality_graph = 
'Interval notation is used to express and graph the solution set of an inequality.  The various possibilities for intervals are shown in the table below'
+'<p><img src="../../image/intervals.gif" alt="intervals"><br>'
+'<img src="../../image/rays.gif" alt="rays"></p>';

var linear_inequality_graph2 = 
'Interval notation is used to express and graph the solution set of an inequality.'
+'The various possibilities for intervals are shown in the table below'
+'</p>';

  var quadratic_equation_graph_of =
  'The graph of a quadratic equation in two variables is a parabola which opens up if '
  +'<span class = "nobr">a > 0</span> and opens down if <span class = "nobr">a < 0.</span>';
  
  var quadratic_equation_intercepts_of =
  'The y-intercept of the graph of a quadratic equation in two variables '
  +'<span class = "nobr">y = ax<sup>2</sup> + bx + c</span> is <span class = "nobr">(0, c).</span><br><br>'
  +'The x-intercepts of the graph of a quadratic equation in two variables '
  +'<span class = "nobr">y = ax<sup>2</sup> + bx + c</span> are found by solving the corresponding '
  +'quadratic equation, <span class = "nobr">0 = ax<sup>2</sup> + bx + c,</span>  in one variable.';
  
  var quadratic_equation_vertex_of =
  'The first coordinate of the vertex of the graph of a quadratic equation in two '
  +'variables <span class = "nobr">y = ax<sup>2</sup> + bx + c </span><br><br>is&nbsp;&nbsp; -b/2a.';
  
  
  var quadratic_equation_discriminant_of =
  'The discriminant of a quadratic equation in two variables <span class = "nobr">y = ax<sup>2</sup> + bx + c </span>'
+'  is  <span class = "nobr">b<sup>2</sup> - 4ac.</span> <br><br>'
+'If the discriminant is positive,the graph has two <span class = "nobr">x-intercepts.</span><br>'
+'If the discriminant is zero,the graph has one <span class = "nobr">x-intercept.</span><br> '
+'If the discriminant is negative,the graph has no <span class = "nobr">x-intercepts</span> and in this case,<br>'
+' &nbsp&nbsp&nbsp&nbsp The graph is entirely above the <span class = "nobr">x-axis</span> if <span class = "nobr">a > 0.</span><br>'
+' &nbsp&nbsp&nbsp&nbsp The graph is entirely below the <span class = "nobr">x-axis</span> if <span class = "nobr">a < 0.</span>';  
  
 
  var quadratic_equation_one_variable_discriminant_of =
  'The discriminant of a quadratic equation in one variable'
+'  <span class = "nobr">ax<sup>2</sup> + bx + c = 0 </span>'
+'  is  <span class = "nobr">b<sup>2</sup> - 4ac.</span> <br><br>'
+'If the discriminant is positive,the equation has two <span class = "nobr">real solutions.</span><br>'
+'If the discriminant is zero,the equation has one <span class = "nobr">real solution.'
+'</span><br> If the discriminant is negative,the graph has no <span class = "nobr">'
+'real solutions</span> and in this case,<br>'
+'the equation has two complex solutions.  Furthermore the complex solutions are complex conjugates. ';  
 
var discriminant_and_law_of_trichotomy=
'Observe that in the above fact, the discriminant is compared to zero.'
+'  According to the Law of Trichotomy exactly one of the following is true:'
+'<ol class=lroman>'
+'<li>the discriminant is greater than 0 (is positive),</li>'
+'<li>the discriminant is equal to 0,</li>'
+'<li>the discrimanant is less than zero (is negative).</li>'
+'</ol>'
+'Therefore according to The Law of Trichotomy all possibilities are considered in the above'
+' fact.';
 
 
 var quadratic_formula =
 'The solutions of a quadratic equation <span class = "nobr"> ax<sup>2</sup> + bx + c = 0 </span> are given by <br><br><br>'
 +'<img class=formula name ="Quadratic_Formula" src="../../image/formula_quadratic_small.gif"  alt="minus b plus or minus the square root of b square minus four a c all divided by 2 a"><br>';
 
 var quadratic_solve_by_factoring =
 'Many quadratic equations in one variable may be solved by using factoring techniques in conjunction with'
 +' the Zero Factor Property as described here:<br><br>'
 +'<ol>'
 +'<li>Write the quadratic equation in standard form.</li>'
 +'<li>Factor the quadratic polynomial into a product of linear factors.</li>'
 +'<li>Use the Zero Factor Property to set each factor equal to zero.</li>'
 +'<li>Solve each of the resulting linear equations.</li>'
  +'</ol>'
 +'The resulting solutions are solutions of the original quadratic equation.';
 
 var equation_solve_by_factoring =
 '<br><br>Some equations may be solved by using factoring techniques in conjunction with'
+' the Zero Factor Property as described here:'
+'<ol>'
 +'<li>Write the equation in standard form</li>'
 +'<li>Factor the polynomial into a product of linear factors</li>'
 +'<li>Use the Zero Factor Property to set each factor equal to zero</li>'
 +'<li>Solve each of the resulting linear equations.</li>'
  +'</ol>'
+'The resulting solutions are solutions of the original equation.'; 

   var zero_factor_property =
 'If a and b are real numbers and ab = 0, then a = 0 or b = 0.';
 
   var zero_quotient_property =
 'A fraction is equal to zero if and only if its numerator is zero.'; 
 
  var polynomial_equation_solving_by_factoring =
   'It is sometimes possible to use factoring in conjunction with the Zero Factor Property to solve a '
   +'polynomial equation.';
   
  var polynomial_equation_solving_by_substitution =
   'It is sometimes possible to substitute a variable for an expression in an equation so that the resulting '
   +'equation is a quadratic equation. That quadratic equation may be solved by normal methods for solving quadratic '
   +'equations. Those results are then substituted back to obtain solutions to the original equation.';
   
  var function_notation_comment1 =
   'The symbol f(x) is read: f of x <br><br>'
   +'Note that the element inside the parenthesis is a single element of the domain<br>'
   +'Note that f(x) is a single element of the range of the function.';   
 
  var function_notation_comment2 =
   ' In reference to the notation above, it is correct to speak of the function f. <br><br>'
   +'In reference to the notation above it is incorrect to speak of the function f(x).';   
  
   var function_notation_comment3 =
   ' <b class = "bold_blue">Function as an Equation:</b> Function notation is most commonly used to state the rule of a function. This use of function notation'
   +' is especially convenient when the rule for the function can be expressed as an equation in terms of the '
   +'domain element. ';  
 
   var function_notation_convention1 =
   'Common practice is to write only the rule for a function with no mention of the domain or range. '
   +'To avoid confusion the following convention has been adopted.  <span class = highlight><b>Unless otherwise stated, the domain of '
   +'a function is the largest set of real numbers for which the rule makes sense (has meaning) and the range '
   +'is the set of real numbers associated with those domain elements</b></span>';  

var evaluating_a_funtion=
  'The expression <b>evaluating a function</b> is an abreviation for <b>evaluating a '
  +'function at a given point</b> which means to <b>determine the range value associated '
  +'with a given domain element</b>. To evaluate a function then means to <b>calulate f(x) '
  +'for a given value of x</b>.  This is particularly easy to do if the rule for the '
  +'function can be expressed as an equation and function notation is used to express '
  +'that equation.';

 var function_calulating_range_values =
   '<span class = normal_text>To calculate the unique range value associated with a domain element one must follow exactly the recipe '
   +'given in the rule of the function.  That means you must perform all operations on the domain element '
   +'which the rule dictates.  Remember the domain element is the entire expression inside the parenthesis.</span>';
 
   var finding_zeros_of_a_function =
 'To find the zeros of a function we must recall the definition of zero of a function. '
 +'That definition tells us to find domain elements x whose corresponding range element f(x) is zero.<br><br>'
 +'Therefore to find the zeros of a function f, we must <br>&nbsp;&nbsp;first solve the equation resulting from f(x) = 0<br>'
 +'&nbsp;&nbsp;and secondly, discard those solutions which are <br>&nbsp;&nbsp;not in the domain of the function'; 
 

   var finding_zeros_of_a_rational_function =
 'To find the zeros of a rational function we use the Zero Quotient Property which states that a fraction is 0 '
 +'if and only if its numerator is 0 and its denominator is not 0. <br>This implies that we must <br>&nbsp;&nbsp;<b>find the zeros of the function in the numerator.</b><br><br>'
 +'Zeros of a function are domain elements so we must discard all zeros of the numerator which are not in the domain of the function f.  '
 +'Therefore we must <br>&nbsp;&nbsp;<b>determine the domain of f.</b> ';  
 
    var possible_rational_zeros =
 'TO BE DELETED If p/q  is a rational zero of a polynomial function with integer coefficients,<br>'
 +' then p must be a divisor of the constant term and q must be a divisor of the leading coeficient.'
  
   var convention_for_the_domain =
 'Unless otherwise stated the domain of a function is the largest set of real numbers for which the rule '
 +'makes sense. ';
 
   var domain_of_polynomial_function =
 'Unless otherwise stated the domain of a function is the largest set of real numbers for which the rule '
 +'makes sense.  <br><br>Therefore the domain of a polynomial function, unless otherwise stipulated, '
 +'is the set of all real numbers . '; 
 
   var domain_of_rational_function =
 'Unless otherwise stated the domain of a function is the largest set of real numbers for which the rule '
 +'makes sense.  <br><br>Therefore the domain of a rational function, unless otherwise stipulated, '
 +'is the set of all real numbers for which the denominator is not zero . ';  
 

 
   var domain_of_function_with_radical =
 'Unless otherwise stated the domain of a function is the largest set of real numbers for which the rule '
 +'makes sense.  <br><br>Therefore the domain of a polynomial function which contains a radical, '
 +'unless otherwise stipulated, is the set of all real numbers for which the expression under the radical is . '
 +'non-negative.';  

var linear_function_vertical_line =
'A vertical line is not the graph of a function.';

var linear_function_graph =
'The graph of a linear function is a non-vertical line and <br><br> conversely every non-vertical line '
+'is the graph of a linear function.';

var linear_function_simple_concept =
'Because lines and linear functions are simple concepts, there are relatively few questions one can ask about them.';

var linear_function_nine_questions =
'<p><b class = "bold_blue">When given a linear function:</b></p>'
+'  <ol>'
+'    <li>Write the rule for the function in the form <span class = "nobr">f(x) = mx + b.</span></li>'
+'	  <li>Sketch the graph of f.</li>'
+'    <li>What is the y-intercept of the graph of f ?</li>'
+'    <li>What is the zero of f ? </li>'
+'    <li>What is the x-intercept of the graph of f ?</li>'
+'    <li>Is f increasing or decreasing ?</li>'
+'  <p><b class = "bold_blue">When asked to determine a linear function:</b></p>'
+'    <li>Determine the rule for the linear function whose graph has a given slope and a given y-intercept.</li>'
+'    <li>Determine the rule for the linear function whose graph has a given slope and contains a given point.</li>'
+'    <li>Determine the rule for the linear function whose graph contains two given points. </li>'
+'  </ol>';

var linear_equations_eight_questions =
'<p><b class = "bold_blue">When given a linear equation in two variables:</b></p>'
+'  <ol>'
+'    <li>Write the equation in two variables in the form <span class = "nobr">y = mx + b.</span></li>'
+'	  <li>Sketch the graph of the equation.</li>'
+'    <li>What is the y-intercept of the graph of the equation ?</li>'
+'    <li>What is the x-intercept of the graph of the equation ?</li>'
+'    <li>Is the graph increasing or decreasing ?</li>'
+'  <p><b class = "bold_blue">When asked to determine a linear equation in two variables:</b></p>'
+'    <li>Determine the equation for the linear equation in two variables whose graph has a given slope and a given y-intercept.</li>'
+'    <li>Determine the equation for the linear equation in two variables whose graph has a given slope and contains a given point.</li>'
+'    <li>Determine the equation for the linear equation in two variables whose graph contains two given points. </li>'
+'  </ol>';


   var looking_for_a_linear_function =
 'To determine a particular linear function use the fact that the rule of the desired function can be written '
 +'in the form <br><center><span class = "nobr">f(x) = mx + b</span></center>where m is the slope of the graph <br>and b is the y-intercept of the graph.<br><br>  '
 +'Then use other information from the problem to determine values for the coefficients m and b '
 +'for the desired function.'; 
 
 var linear_function_determine =
  'The rule of a linear function can be written in the form <br><center><span class = "nobr">f(x) = mx + b</span></center>'
  +'where m is the slope of the graph <br>and b is the y-intercept of the graph.<br><br>'
  +'To <b class = "bold_blue">determine</b>'
  +'  a particular linear function means to determine values for both of the coefficients m and b.  ';
 
 var linear_function_partially_determine =
  'The rule of a linear function can be written in the form <br><center><span class = "nobr">f(x) = mx + b</span></center>'
  +'where m is the slope of the graph <br>and b is the y-intercept of the graph.<br><br>'
  +'To <b class = "bold_blue">partially determine</b> a particular linear function means to determine values '
  +'for one of the coefficients m and b.  '; 
  
 var linear_function_graphing =
  'To graph a linear function it is only necessary to plot two points on the graph and draw the line through those '
  +'points.<br><br>  The x-intercept is always important so it should be plotted and labeled.<br><br>  The y-intercept is easy to '
  +'determine, so it is a good point to plot and label.';

 var linear_equation_two_variables_graphing =
  '<span class=popup_text>To graph a linear equation in two variables it is only necessary to plot two points on the graph and draw the line through those '
  +'points.<br><br>  The x-intercept is always important so it should be plotted and labeled.<br>  The y-intercept is easy to '
  +'determine, so it is a good point to plot and label.</span>';

 var linear_inequality_two_variables_graphing =
  '<span class=popup_text>To graph a linear inequality in two variables it is only '
  +'necessary to graph the boundary equation and test a point, called the test point, not '
  +'on the boundary line.<br><br> If the test point is a solution of the inequality every '
  +'point in that half-plane is a solution and that half-plane is the graph of the '
  +'inequality.<br> If the test point is not a solution of the inequality every point in '
  +'the other half-plane is a solution of the inequality and the graph is that other '
  +'half-plane.';

  var quadratic_function_graph_of =
  'The graph of a quadratic function is a parabola which opens up if '
  +'<span class = "nobr">a > 0</span> and opens down if <span class = "nobr">a < 0.</span>';
  
  var quadratic_function_intercepts_of =
  'The y-intercept of the graph of a quadratic function '
  +'<span class = "nobr">f(x) = ax<sup>2</sup> + bx + c</span> is <span class = "nobr">(0, c).</span><br><br>'
  +'The x-intercepts of the graph of a quadratic function '
  +'<span class = "nobr">f(x) = ax<sup>2</sup> + bx + c</span> are found by solving the corresponding '
  +'quadratic equation in one variable, <span class = "nobr">ax<sup>2</sup> + bx + c = 0.</span>';
  
  var quadratic_function_vertex_of =
  'The first coordinate of the vertex of the graph of a quadratic function '
  +' <span class = "nobr">f(x) = ax<sup>2</sup> + bx + c </span> is -b/2a.<br>'
  +'Because the vertex is on the graph of the function, the second coordinate is the range value associated with the first coordinate.<br>'
  +'Therefore the vertex is <img src="../../image/vertex_parabola_small.gif" align="absmiddle">.';
  
var quadratic_function_vertex_location_of =
  'There are several convenient ways to locate the vertex of the graph of a quadratic function:'
  +'<ol>'
	+'<li>The vertex is on the line of symmetry of the parabola.</li>'
	+'<li>If the graph has two <span class = "nobr">x-intercepts,</span> the first coordinate of the vertex is midway between the two intercepts.</li>'
	+'<li>If the graph has one <span class = "nobr">x-intercept,</span> that intercept is the vertex.</li>'
	+'<li>The vertex is <img src="../../image/vertex_parabola_small.gif" align="absmiddle">.</li>'
  +'</ol>';
  

  
  
  var quadratic_function_discriminant_of =
  'The discriminant of a quadratic function <span class = "nobr">f(x) = ax<sup>2</sup> + bx + c </span>'
+'  is  <span class = "nobr">b<sup>2</sup> - 4ac.</span> '
+'<ol>'
+'<li>If the discriminant is positive,the graph has two <span class = "nobr">x-intercepts.</span>'
+'<li>If the discriminant is zero,the graph has one <span class = "nobr">x-intercept.</span><br> '
+'<li>If the discriminant is negative,the graph has no <span class = "nobr">x-intercepts</span> and in this case;'
+'<ol class=lroman>'
+' <li>The graph is entirely above the <span class = "nobr">x-axis</span> if <span class = "nobr">a > 0.</span>'
+' <li>The graph is entirely below the <span class = "nobr">x-axis</span> if <span class = "nobr">a < 0.</span>'  
+'</ol>'
+'</ol>';

 var quadratic_function_graphing =
  'To graph a quadratic function remember the graph of a quadratic function is '
  +'a parabola which opens up if the leading coefficient is positive and opens down if the leading coefficient '
  +'is negative.  The x-intercepts are always important so they should be found, plotted, and labeled.<br><br>'
  +'The x-intecepts of any function are found by finding the real zeros of the function.<br><br> '
  +'The zeros of any function f are found by solving the equation resulting from f(x) = 0.<br><br>'
  +'In the case of a quadratic function f the equation resulting from f(x) = 0 is always solvable with the '
  +'Quadratic Formula or by factoring in conjunction with the Zero Factor Property.<br><br>'
  +'The vertex of the parabola is also important and should always be found, plotted, and labeled.<br>'
  +'The vertex is <img src="../../image/vertex_parabola_small.gif" align="absmiddle">.' ;

 var polynomial_function_graphing =
  'To graph a polynomial function remember the graph of a polynomial function is a smooth continuous curve with '
  +'no sharp corners.  The graph of a polynomial function tries to cross the x-axis the same number of times as '
  +'the degree of the polynomial.<br><br>  The x-intercepts are always important so, if possible, they should be '
  +'found, plotted, and labeled.<br><br>'
  +'The x-intecepts of any function are found by finding the real zeros of the function.<br><br> '
  +'The zeros of any function f are found by solving the equation resulting from<br><center>f(x) = 0</center>.<br>'  
  +'Factoring in conjunction with the Zero Factor Property is the primary tool for solving the resulting '
  +'polynomial function.<br><br>' 
  +'If the function is a simple variation of a familiar function, that information can sometimes be used '
  +'to help sketch the graph.';

   var rule_for_a_function =
 'A rule which associates each element of the domain with a unique element of the range. ';
 
 var division_algorithm_for_polynomials =
 'If p and d are polynomials with real coefficients, then there are unique polynomials q and r with real coefficients'
 +' such that <p class = display><span class = "nobr">p = qd + r</span></p> <br>'
 +'with <span class = "nobr">r = 0</span> or the degree of r is less than the degree of d.';
 
 var division_algorithm_for_natural_numbers =
 'If a and b are natural numbers then there are unique natural numbers q and r such that <p class = display><span class = "nobr">a = bq + r with 0 &le; r < b.</span></p>';


var leading_term_dominates =
 'For domain elements far from the origin, the leading term in a polynomial function dominates' 
 +' the entire expression when calculating range elements.';
 
  var smooth_graph =
 'The graph of a polynomial function is a continuous smooth curve with no sharp corners.';
 
   var tries_to_cross_the_axis_n_times =
 'The graph of a polynomial function f of degree n can have no more than n <span class = "nobr">x-intercepts.</span><br>'
 +'  The graph “tries” to have exactly n <span class = "nobr">x-intercepts.</span>';
 
   var humps =
 'The graph of a polynomial function f of degree n can have no more than <span class = "nobr">n - 1</span> humps (turning points).<br>'
 +'  The graph “tries” to have exactly <span class = "nobr">n - 1</span> humps.'; 
 
   var multiplicity_and_intercepts =
 'If the multiplicity of a real zero is an odd number the graph crosses the <span class = "nobr">x-axis</span> at that zero.<br><br>'
 +'If the multiplicity of a real zero is an even number the graph intersects but does not cross'
 +' the <span class = "nobr">x-axis</span> at that zero.';
 
   var multiplicity_odd =
 'If the multiplicity of a real zero is an odd number the graph crosses the <span class = "nobr">x-axis</span> at that zero.';
   var multiplicity_even = 
 'If the multiplicity of a real zero is an even number the graph intersects but does not cross'
 +' the <span class = "nobr">x-axis</span> at that zero.';
 
 
 var intermediate_value_theorem =
  '<br><br>Let a and b be real numbers such that <span class = "nobr">a < b.</span> <br>If f is a polynomial function such that <span class = "nobr">f(a) &ne; f(b)</span>then, '
  +'<br>in the interval <span class = "nobr">[a, b]</span> &nbsp;f takes on every value between <span class = "nobr">f(a)</span> and <span class = "nobr">f(b).</span>';
 
 var intermediate_value_theorem_xintercepts =
  'If f is a polynomial function such that <span class = "nobr">f(a) < 0</span> and <span class = "nobr">f(b) > 0,</span> then f has an <span class = "nobr">x-intercept</span> (a real zero) between a and b.';
 
 
   var analysis_step1 =
 'Observe the kind of function being investigated and note the obvious consequenses of that classification.';

   var analysis_step2 =
 'Try to determine behavior far from the origin.';
 
   var analysis_step3 =
 'Try to determine zeros of the function.<br>'
 +'Take advantage of any special considerations that are peculiar to the type of function being investigated.<br>'
 +'For example, use the Possible Rational Zeros property when dealing with polynomials.' ;
 

 
 
 
 
   var analysis_step4 =
 'When working with a polynomial function:<br>'
 +'As soon as a zero is found, factor out the corresponding factor, so you can work with a polynomial of smaller degree.'
 +'<br>Use long division or synthetic division whichever is most comfortable for you.' ; 
 
   var analysis_summary_step =
 'Summarize everything you have discovered in the search for zeros<br>'
 +'Use that information to sketch the graph of the function.<br>'
 +'<br>Be aware that for functions other than polynomials some other considerations may be required.' ;  
 
   var graph_with_factors =
 'It is helpful to look at the graph of the function being studied with graphs of its factors superimposed.<br>'
 +'The correlation of the zeros is an important observation.<br>';  
 
   var greater_than_less_than =
 'The graphs of the factors can show where the graph of the function being studied is'
 +' above the <span class = "nobr">x-axis</span> and where it is below the <span class = "nobr">x-axis.</span><br><br>'
 +' This observation is used to determine where <span class = "nobr">f(x) > 0</span> and where <span class = "nobr">f(x) < 0</span>';  
 
var vertical_asymptote_fact1 =
 'Vertical asymptotes of a rational function occur at the real zeros of the denominator which are not zeros '
+'of the numerator.';

var vertical_asymptote_finding = 
 'To find the vertical asymptotes of a rational function find the real zeros of the denominator '
 +'and eliminate those which are also zeros of the numerator.';
 
 var horizontal_asymptote_finding = 
 'To find a horizontal asymptote of a rational function <p class = display><img src="../../image/function_rational2_small.gif" align="absmiddle">:</p>'
  +'<ol>'
  +'<ol>'
  +'<li> If <span class = "nobr">m < n,</span> the line <span class = "nobr">y = 0</span> is a horizontal asymptote.</li>'
  +'<li> If <span class = "nobr">m = n,</span> the line <img src="../../image/horizontal_asymptote_equation_small.gif" align="absmiddle"> is a horizontal asymptote.</li>'
  +'<li> If <span class = "nobr">m > n,</span> there is no horizontal asymptote.</li>'
  +'</ol>'
  +'</ol>';
 
 var real_zeros_equivalent_statements =
 'If f is a polynomial function whose rule is given by '
 +'<p class = display><span class = "nobr">f(x) = a<sub>n</sub>x<sup>n</sup> + a<sub>n-1</sub>x<sup>n-1</sup> + ... +a<sub>1</sub>x + a<sub>0</sub></span></p>'
 +'then the following statements are equivalent.'
 +'<ol><ol>'
 +'<li> k is a real zero of the function f.</li>'
 +'<li> k is a solution of the polynomial equation <span class = "nobr">a<sub>n</sub>x<sup>n</sup> + a<sub>n-1</sub>x<sup>n-1</sup> + ... +a<sub>1</sub>x + a<sub>0</sub> = 0.</span><br><br><br></li>'
 +'<li> <span class = "nobr">x - k</span> is a factor of the polynomial <span class = "nobr">a<sub>n</sub>x<sup>n</sup> + a<sub>n-1</sub>x<sup>n-1</sup> + ... +a<sub>1</sub>x + a<sub>0</sub>.</span><br><br></li>'
 +'<li> <span class = "nobr">(k, 0)</span> is an <span class = "nobr">x-intercept</span> of the graph of the function f.<br></li>'
 +'</ol></ol>'



   var finding_horizontal_asymptotes1 =
 'To find a horizontal asymptote of a rational function:<br>'
+'&nbsp;&nbsp;    1.  Divide each term of the numerator and each term of the denominator by the highest power of x in the denominator<br> ' 
+'&nbsp;&nbsp;    2.  Determine the behavior as x increases (or decreases) without bound by observing which terms approach zero';

var rational_function_fact1 =
'The graph of a function f cannot intersect any of its vertical asymptotes.';

var rational_function_fact2 =
'The graph of a function f may intersect  its horizontal asymptote.';

var rational_function_fact3 =
'The graph of a function f need not intersect its horizontal asymptote but it may intersect its horizontal '
+'asymptote any number of times, including infinitely many times.';

var rational_function_fact4 =
'If a zero of the denominator of a rational function is also a zero of the numerator, then there is no '
+'vertical asymptote at that point. Rather there is a &quot;hole&quot; in the graph, that is just one point '
+'is missing in the graph.';

var rational_function_fact5 =
'The zeros of a rational function are the zeros of its numerator which are not also zeros of the denominator.';

var rational_function_graphing_procedure =
'<ol>'
+'  <li>Find the zeros of the numerator, note which are real numbers</li>'
+'  <li>Plot the real zeros and label them, because they are <span class = "nobr">x-intercepts</span> of the function</li>'
+'  <li>Find the zeros of the denominator, note which are real numbers and note which are not also zeros of the numerator</li>'
+'  <li>Plot the real zeros of the denominator and erect vertical lines through those which are not zeros of the numerator. These are the vertical asymptotes.</li>'
+'  <li>Erect vertical lines through each of the <span class = "nobr">x-intercepts.</span></li>'
+'  <li>Note that the vertical lines through the <span class = "nobr">x-intercepts</span> and the vertical asymptotes divide the plane into several strips</li>'
+'  <li>Pick a convenient number in each strip and calculate its corresponding range element,'
+'    <ul class=disc>'
+'      <li>If this range element is positive, exclude the lower half of the strip-the part below the <span class = "nobr">x-axis</span></li>'
+'      <li>If this range element is negative, exclude the upper half of the strip-the part above the <span class = "nobr">x-axis</span></li>'
+'    </ul>'
+'  </li>'
+'  <li>Determine the horizontal asymptote, if any, using the conditions'
+'    <ul class=disc>'
+'		<li> If <span class = "nobr">m < n,</span> the line <span class = "nobr">y = 0</span> is a horizontal asymptote.</li>'
+'		<li> If <span class = "nobr">m = n,</span> the line <img src="../../image/horizontal_asymptote_equation_small.gif" align="absmiddle"> is a horizontal asymptote.</li>'
+'		<li> If <span class = "nobr">m > n,</span> there is no horizontal asymptote.</li>'
+'    </ul>'
+'  </li>'
+'  <li>Sketch the graph by drawing only in the regions which have not been excluded. Be sure to draw through the <span class = "nobr">x-intercepts</span> and be sure to indicate all asymptotic behavior.</li>'
+'	<li>Label all important points and lines. That means to provide coordinates, intercepts, and equations as appropriate.  </li>'
+'</ol>'






var identifying_an_object=
 'To determine if an object is a particular creature, it is necessary to compare the object with the definition'
 +' of the creature.';
 
var mathematical_operations =
 'The four operations in mathematics are addition, subtraction, multiplication, and division.<br>'
 +'Subtraction and division are inverses of addition and multipliction and are defined in terms of addition '
 +'and multiplication.<br><br>'
 +'+ is the symbol for addition.<br>'
 +'- is the symbol for subtraction.<br>'
 +'The fraction bar, <IMG src="../../image/symbol_division.gif" width=62 height=26 align=Absmiddle> '
 +'are symbols for division.<br>'
 +'The symbols <IMG src="../../image/symbol_multiplication.gif" width=62 height=12 align=Absmiddle> '
 +'are used to indicate multiplication.&nbsp;&nbsp;When there is no chance of confusion, multiplication '
 +'is indicated by simple juxtaposition.'; 
 
var multiplication_symbols =
 'The symbols <IMG src="../../image/symbol_multiplication.gif" width=62 height=12 align=Absmiddle> '
 +'are used to indicate multiplication.&nbsp;&nbsp;<br><br>When there is no chance of confusion, multiplication '
 +'is indicated by simple juxtaposition.'; 
 
var division_symbols =   
 'The fraction bar, <IMG src="../../image/symbol_division.gif" width=62 height=26 align=Absmiddle> '
 +'are symbols for division.<br>';
 
var building_an_equation =
 'Translating a verbal statement into an equation is always accomplished by <span class = highlight> finding two '
 +'algebraic expressions for some single quantity</span> in the verbal statement. Since these two expressions '
 +'represent the same quantity, they are equal.<br><br>'
 +' Expressing that equality with an = symbol produces '
 +'the desired equation.';
 
var advantage_of_equation =
 'When variables are assigned to the quantities in a particular problem and an equation is derived, '
 +'the problem has been divorced from the particular application and is at that point a purely mathematical problem. '
 +'All peculiarities of the application are stripped away so as not to confuse or interfere with the solution process.';
 
var problem_solving_strategy =
'<ol class = "decimal">'
+'<li>Understand the problem.</li>'
   +'<ul class = "disc">'
     +'<li>Read and reread the problem understanding every word.</li>'
     +'<li>Make sketches and drawings even if only symbolic.</li>'
   +'</ul>'
+'<li>Assign a variable to the quantity to be determined.</li>'
   +'<ul class = "disc">'
     +'<li>List the known quantities.</li>'
     +'<li>List the unknown quantities.</li>'
     +'<li>Observe/list relationships between quantities.</li>'
     +'<li>Determine which of the unknown quantities is to be determined.</li>'	 
   +'</ul>'
+'<li>Express all other unknown quantities in terms of this variable.</li>'
+'<li>Translate the problem into an equation.</li>'
   +'<ul class = "disc">'
     +'<li><span class="highlight">Use known and unknown quantities to express some single quantity in two different ways.</span></li>'
     +'<li><span class="highlight">Since these two expressions represent the same quantity, they are equal.</span></li>'
   +'</ul>'
+'<li>Solve the equation.  (Forget about the application problem during this step)</li>'
+'<li>Interpret the solution in terms of the problem.</li>'
+'<li><span class="highlight">State the conclusion.</span></li>'
+'</ol>'; 
 
 


var vertical_line_test =   
 'If a vertical line may be drawn so that it intersects a graph in more than one point, then that graph is not '
 +'the graph of a function.';

var function_one_to_one_comment1 =   
 'To show algebraically that a function is <span class = "nobr">one-to-one,</span> it is necessary to prove that for any two domain elements '
 +'a and b, <span class = "nobr">f(a) = f(b)</span> implies that <span class = "nobr">a = b.</span><br><br>'
 +'It generally is easier to use the Horizontal Line Test.'; 

var function_one_to_one_comment2 =   
 'To show algebraically that a function is NOT <span class = "nobr">one-to-one,</span> it is only necessary to find a range element which '
 +'could be the correspondent of more than one domain element.';


var horizontal_line_test =   
 'If a horizontal line may be drawn so that it intersects the graph of a function in more than one point, '
 +'then the function does not have an inverse.<br><br>'
 +'If no horizontal line intersects the graph of a function f in more than one point, <br>then the function f '
 +'has an inverse f<sup>-1</sup>.';
 
var horizontal_line_test_expanded =   
 'If a horizontal line may be drawn so that it intersects the graph of a function in more than one point, '
 +'then the function is not a <span class = "nobr">one-to-one</span> function and hence does not have an inverse.<br><br>'
 +'If no horizontal line intersects the graph of a function f in more than one point, <br>then the function f '
 +'is a <span class = "nobr">one-to-one</span> function and hence has an inverse <span class = "nobr">f<sup>-1</sup>.</span>'; 
 
var function_inverse_comment1 =   
 'The inverse of a function is the inverse with respect to composition. ';
var function_inverse_comment2 =   
 'From the symmetrical nature of the above definition it is clear that <span class = "nobr">f<sup>-1</sup></span> is the inverse of f and  '
 +'conversely, f is the inverse of <span class = "nobr">f<sup>-1</sup>.</span>';
var function_inverse_comment3 =   
 'The functions f and <span class = "nobr">f<sup>-1</sup></span> are inverses of each other. '; 
var function_inverse_comment4 =   
 'Not all functions have inverses. '; 
var function_inverse_comment5 =   
 'The symbol <span class = "nobr">f<sup>-1</sup></span> is read as <b class = "bold_blue">f inverse.</b> '; 
var function_inverse_comment6 =   
 'A function f has an inverse if and only if the function f is <span class = "nobr">one-to-one.</span>'; 
var function_inverse_comment7 =   
 'In terms of our fundamental "arrow" description of a function this means that no range element has more than one arrow ending at it.'; 
var function_inverse_comment8 =   
 'The horizontal line test is a test to determine if a function is <span class = "nobr">one-to-one.</span>'; 
var function_inverse_finding =   
 'The following steps constitute a method for Finding the Inverse of a Function. <br><br>Suppose the function is named f.<br><br> '
+'<ol>'
+'<li>Use the Horizontal Line Test to determine if f has an inverse.</li>'
+'<li>In the rule for f, replace <span class = "nobr">f(x)</span> with a single variable y.</li>'
+'<li>Interchange x and y.</li>'
+'<li>Solve the equation for y.</li>'
+'<li>Replace y with <span class = "nobr">f<sup>-1</sup></span> to obtain the rule for <span class = "nobr">f<sup>-1</sup></span>.</li>'
+'</ol>'; 
var function_inverse_verification =   
 'To verify (prove) that two functions f and <span class = "nobr">f<sup>-1</sup></span> are inverses of each other it is necessary to show '
 +'that both of the following are true: <br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;<img src="../../image/function_inverse_is_small.gif" align="absmiddle"><br>'
 +'To verify that two functions f and g are NOT inverses of each other it is only necessary to show that ONE '
 +'of the above conditions is false.  That is, it is only necessary to verify one of the following: <br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;<img src="../../image/function_inverse_not_small.gif" align="absmiddle">';


var function_inverse_comment9 =   
 'Replacing f(x) with a single variable y is for convenience only. The entire process can be carried out without '
 +'such replacement, but the notation becomes awkward.'; 
var function_inverse_comment10 =   
 'It is INCORRECT to speak of an inverse function. Just as it is incorrect to speak of 3/4 as an inverse.<br><br>'
+'It is correct to speak of the inverse of a function. Just as it is correct to speak of 3/4 as the inverse of 4/3.<br>' 
+'Thus in the above process we find the inverse of a function.';



var rectangle_perimeter=
 'If x is the length and y is the width of the rectangle then the area is:&nbsp;&nbsp;  <b class = "bold_blue">P = 2x + 2y</b>.';
 
var rectangle_area=
 'If x is the length and y is the width of the rectangle then the area is:&nbsp;&nbsp;  '
 +'<b class = "bold_blue">A = xy</b>.'; 
 
var coordinate_system=
'A rectangular coordinate system (Cartesian coordinate system) consists of two perpendicular number lines.  '
+'One number line is drawn horizontally and the other is drawn vertically.  '
+'The point where these number lines intersect is the 0 point on each number line.<br><br><br>'
+'The horizontal number line is usually called the x-axis.<br><br>'
+'The vertical number line is usually called the y-axis.<br><br>'
+'<center><IMG src="../../image/coordinate_system_small.gif" align=Absmiddle></center> '
+'The point of intersection of the two number lines is called the origin of the coordinate system.<br><br>'
+'The two axis form a coordinate plane and divide it into four quadrants named Quadrant I, Quadrant II, '
+'Quadrant III, and Quadrant IV as shown in the diagram here.<br><br>'
+'<center><IMG src="../../image/quadrants_small.gif" align=Absmiddle></center>';


var point_plotting=
'To associate an ordered pair <span class=nobr>(a, b)</span> of real numbers with a point in the rectangular '
+'coordinate system one performs the following steps:'
+'<ol>'
+'	<li>Locate the first coordinate on the horizontal axis.</li>'
+'	<li>Draw a vertical line through that point on the horizontal axis.</li>'
+'	<li>Locate the second coordinate on the vertical axis.</li>'
+'	<li>Draw a horizontal line through that point on the vertical axis.</li>'
+'	<li>The point where the two lines intersect is the point associated with the ordered pair.</li>'
+'</ol>'
+'<br>The process is illustrated below.'
+'<br><br><center><IMG src="../../image/point_plotting_small.gif" align=Absmiddle></center>'
+'<p>The numbers a and b are called <span class=highlight>coordinates</span> of the point.  The number a is called the '
+'<span class=highlight>first coordinate</span> and the number b is called the <span class=highlight>second coordinate</span>.</p>';

var coordinates_of_a_point=
'To associate a point in the rectangular coordinate system with an ordered pair '
+'<span class=nobr>(a, b)</span> of real numbers one performs the following steps:'
+'<ol>'
+'	<li>Draw a vertical line through the point to intersect the horizontal axis.</li>'
+'	<li>The number represented by the point of intersection is the first coordinate of the point.</li>'
+'	<li>Draw a horizontal line through the point to intersect the vertical axis.</li>'
+'	<li>The number represented by the point of intersection is the second coordinate of the point.</li>'
+'</ol>'



var points_ordered_pairs=
'Each ordered pair of real numbers corresponds to exactly one point in the Cartesian '
+'coordinate system and conversely each point in the Cartesian coordinate system '
+'corresponds to exactly one ordered pair of real numbers.';


var linear_equation_slope_intercept_form=
 'A linear equation in two variables may be written in the form <b class = "bold_blue">'
 +'<span class = "nobr">y = mx + b</span></b> where m is the slope and b is the '
 +'<span class = "nobr">y-intercept.</span> This is called the slope-intercept form.';  

var linear_equation_standard_form=
 '<span class = popup_text>A <b class = "bold_blue">linear equation in two variables</b> may be written in the form '
 +'<span class = "nobr">Ax + By = C</span> where A, B, and C are real numbers and B '
 +'is not zero. This is called the standard form.</span> '; 


var linear_inequality_two_variable_standard_form =
  'A <b class = "bold_blue">linear inequality in two variables</b>'
  +'  x and y is an inequality which can be written as <br><br>' 
  +'<span class = nobr>Ax + By < C</span> or  &nbsp;&nbsp;'
  +'<span class = nobr>Ax + By > C</span> where A, B, and C are real numbers and B is not zero.'
  +' This is called the standard form.';  


var linear_equation_point_slope_form =
 'The equation for the line through the point <span class = "nobr">(x<sub>1</sub>, y<sub>1</sub>)</span> with slope m is'
 +' <b class = "bold_blue"><span class = "nobr">y - y<sub>1</sub> = m(x - x<sub>1</sub>)</span></b>. This is called the point-slope form.' ; 
 
var linear_equation_two_points =
 'The equation for the line through the points <span class = "nobr">(x<sub>1</sub>, y<sub>1</sub>)</span> and  <span class = "nobr">(x<sub>2</sub>, y<sub>2</sub>)</span> is '
 +' found by computing the slope of the line through the two points and then using the <span class = "nobr">point-slope</span> form of the '
 +'equation of a line.' ;  
 
var linear_equation_graph=
 '<span class=popup_text>The graph of every linear equation in two variables is a non-vertical line.<br><br>'
 +'Conversely, every non-vertical line is the graph of some linear equation in two variables.</span>';  
 
var vertical_line=
 'The graph of an equation of the form <span class = "nobr">x = k</span> is a vertical line through the point <span class = "nobr">(0, k)</span> <br><br>'
 +'Conversely, the equation for the vertical line through the point <span class = "nobr">(0, k)</span> is <span class = "nobr">x = k.</span>';  
 
var vertical_line_slope=
 'A vertical line has no slope.';  
 
var horizontal_line_slope=
 'The slope of a horizontal line is 0.';   
 
var parallel_lines=
 'Two <span class = "nobr">non-vertical</span> lines are parallel if they have the same slope and different <span class = "nobr">y-intercepts.</span>';    
 
var perpendicular_lines=
 'Two non-vertical lines are perpendicular if their slopes are negative reciprocals of each other.';  
 
var half_plane_graph=
 'The graph of an inequality in two variables is a <span class = "nobr">half-plane.</span>';   

var boundary_line_linear_inequality=
'The boundary curve for a linear inequality in two variables is a line.';

var boundary_line_and_graph=
 'The boundary line forms the boundary between the <span class = "nobr">half-plane</span> '
 +'consisting of all solutions of the "less than" inequality and the '
+' <span class = "nobr">half-plane</span> consisting of all solutions of the "greater '
+'than" inequality. ';
 

var procedure_for_graphing_linear_inequalities_in_two_variables=
'To graph a linear inequality in two variables:'
+'<ol class=ualpha>'
+'	<li>Sketch the graph of the boundary line.'	
+'		<ol class=lalpha>'
+'			<li>Find the <span class=nobr>y-intercept.</span> (Set <span class=nobr>x = 0,</span> solve for y)</li>'
+'			<li>Find the <span class=nobr>x-intercept.</span> (Set <span class=nobr>y = 0,</span> solve for x)</li>'
+'			<li>Draw the boundary line by connecting the intercepts.'
+'				<ol class=lroman>'
+'					<li>As a solid line if the inequality symbol is either <IMG src="../../special_topics/symbols/greateq.gif"> or <IMG src="../../special_topics/symbols/lesseq.gif"></li>'
+'					<li>As a dashed line if the inequality symbol is either < or ></li>'
+'				</ol>'
+'			</li>'
+'		</ol>'
+'	</li>'	
+'	<li>Pick a point, not on the boundary line, as a test point and substitute its coordinates into the inequality. </li>'	
+'	<li>If the result from Step B is a TRUE statement, the <span class=nobr>half-plane</span> containing the test point is the solution set </li>'	
+'	<li>If the result from Step B is a FALSE statement, the <span class=nobr>half-plane</span> which does not contain the test point is the solution set. </li>'	
+'	<li>Shade the <span class=nobr>half-plane</span> which is the solution set and label all important points with their coordinates. </li>'	
+'</ol>'

var square_of_a_sum =
'(a + b)<sup>2</sup> = a<sup>2</sup> + 2ab + b<sup>2</sup>';

var square_of_a_difference =
'(a - b)<sup>2</sup> = a<sup>2</sup> - 2ab + b<sup>2</sup>';

var product_of_sum_and_difference =
'(a + b)(a - b) = a<sup>2</sup> - b<sup>2</sup>';

var sum_of_cubes =
'a<sup>3</sup> + b<sup>3</sup> = (a + b)(a<sup>2</sup> - ab + b<sup>2</sup>)';

var difference_of_cubes =
'a<sup>3</sup> - b<sup>3</sup> = (a - b)(a<sup>2</sup> + ab + b<sup>2</sup>)';

//INDEX_FACTORING
var to_factor_polynomial=
 'To factor a polynomial means to write the polynomial as a product.';
 
var factoring_polynomial=
 'Factoring a polynomial is a trial and error procedure.  The only way to determine if a factorization is '
 +'correct is to multiply the factors and compare that product with the original polynomial.<br><br><br>'
 +'Several techniques which reduce the number of errors in the trial and error procedure.'
 +'<ul class=disc>'
 +'<li>Use of the Distributive Law</li>'
 +'<li>Knowledge of Special Products</li>'
 +'<li>Grouping</li>'
 +'<li>Knowledge of Multiplication Facts</li>'
 +'</ul>';
 
var representation_different_number=
 'There are many ways to represent a number. <br><br>'
 +'Presented here are several ways of representing the number 6.<br>'
 +'6 <br>'
 +'3 + 3<br>'
 +'1 + 1 + 1 + 1 + 1 + 1<br>'
 +'(2)(3)<br>'
 +'(1)(6)<br>'
 +'18/3<br>'
 +'Each of the above represents the number six and they may be used interchangably.  <br>'
 +'The context determines which representation to use.<br>';
 

 
var factoring_polynomial_what_is_it= 
 'You have probably already learned that a very useful representation for a natural number is its '
 +'prime factorization. Notice that when we write the prime factorization of a natural number, we are '
 +'representing that number as a <B>PRODUCT</B>	 of prime factors.  In the same manner, it is frequently '
 +'desirable to represent a polynomial as a <B>PRODUCT</B> of prime factors.<br><br>'
 +'The process of determining the factors of a polynomial and representing that polynomial as a '
 + '<B>PRODUCT</B> of those factors is called <b class = "bold_blue">factoring the polynomial.</b>';
 
var factoring_common_factors =
 'A sum (or difference) of terms may be written as a product by factoring out any factors common to each term.'; 
 
var factoring_reversing_multiplication=
 'Factoring a term out of a sum (or difference) of terms is reversing a multiplication done with the '
 +'distributive property.';
 
var factoring_trinomial_easy =
 'To factor a trinomial of the form <span class="nobr">x<sup>2</sup> + bx + c</span> into a product of two linear factors of the form <span class="nobr">x + k</span> '
 +'and <span class="nobr">x + h</span> we proceed as follows:<br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1)   Find two integers h and k whose product is c and whose sum is b.<br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2)   Write the factorization using the appropriate choice of signs so the '
 +'product is equal to the trinomial.';
 
var determining_the_constants =
 'To factor a trinomial of the form <span class="nobr">x<sup>2</sup> + bx + c</span> into a product of two linear factors of the form <span class="nobr">x + k</span> '
 +'and <span class="nobr">x + h</span> the numbers h and k must be factors of the constant term c. <br><br>Their product hk must be c and their sum '
 +'<span class="nobr">h + k</span> must be b. ';
 
var determining_the_signs =
 'If the sign of the constant term c in a trinomial of the form x<sup>2</sup> + bx + c is positive then the signs '
 +'in the two linear factors must be the same.  In this case the sign in both linear factors must be the same as '
 +'the sign of b (the linear term in the trinomial).<br><br>'
 +'If the sign of the constant term c in a trinomial of the form x<sup>2</sup> + bx + c is negative then '
 +'the two linear factors must have opposite signs.  One of the linear factors must have a positive sign '
 +'and the other must have a negative sign.'; 
 
var factoring_trinomial_hard=
 'To factor a trinomial of the form <span class="nobr">ax<sup>2</sup> +bx + c</span> into a product of two linear factors of the form <span class="nobr">px + k</span> '
 +'we proceed as follows:<br><br>'

 +'<IMG src="../../image/factoring_general_process.gif" width=590 height=225 align=Absmiddle><br><br>';
 
var factoring_trinomial_hard_example=
 'The following elaborate example illustrates some of the difficulties with factoring second degree polynomials.<br><br>'
  +'<IMG src="../../image/factoring_trinomial_example.gif" width=773 height=1050 align=Absmiddle>';
 
var factoring_by_grouping =
 'To factor a polynomial with four or more terms a technique called <b class = "bold_blue">'
 +'Factoring by Grouping</b> is sometimes productive. '
 +' After factoring out the GCF the procedure is as follows:'
 +'<ol>'
 +'<li>Group pairs of terms with common factors,</li>'
 +'<li>Factor out the GCF in each group,</li>'
 +'<li>If the groups contain a common factor use the Distributive Law to complete '
 +'the factorization.</li>' 
 +'</ol>'; 
 
var testing_a_conditional_equation =
 'An equation is either an identity or a conditional equation.  If a number is found which is not a solution ' 
 +'of the equation, then the equation is not an identity and must therefore be a conditional equation.';

var verify_an_identity =
 'An equation is either an identity or a conditional equation.  To verify that an equation is an identity it '
 +'is necessary to generate a series of equivalent equations culinating in an equation whcih has identical '
 +'expressions on the two sides.';

 
var strategy_exercise_1_1_56 = 
 'To write the equation of a circle it is necessary and sufficient to know the radius and the center.  '
 +'In this problem the center is the midpoint of a diameter.  We can find the center by using the formula <br><br>'
 +'<IMG src="../../image/formula_midpoint.gif" width=123 height=47 align=Absmiddle> to find the midpoint of the '
 +' given diameter.<br><br>The radius may be calculated as one-half of the length of the diameter or as the '
 +'distance from the center to either endpoint.';
 
var strategy_exercise_1_1_58 = 
 'To find the center and radius of the circle we must recognize the equation as the equation of a circle and then '
 +'we must compare this equation with one of the standard equations for a circle. <br><br>'
 +'x<sup>2</sup> + y<sup>2</sup> = r<sup>2</sup>  <br>or<br> (x - h)<sup>2</sup> + (y - k)<sup>2</sup>= r<sup>2</sup>.';

	   


var comment_exercise_1_2_54 =
 'Notice that the three signs of a fraction tell us that <br>'
 +'<IMG src="../../college_algebra/exercises/images_for_exercises/1_2_54e.gif" width=165 height=40 align=Absmiddle><br>' 
 +'That information is then used to write the fraction '
 +'<IMG src="../../college_algebra/exercises/images_for_exercises/1_2_54d.gif" width=20 height=40 align=Absmiddle>'
 +'in the more familiar form '
 +'<IMG src="../../college_algebra/exercises/images_for_exercises/1_2_54c.gif" width=27 height=37 align=Absmiddle>';
  
var comment_exercise_1_1_56 =
 'In case you are wondering how I got 17.  Notice that as a result of the definition of  <br>'
 +'<IMG src="../../college_algebra/exercises/images_for_exercises/1_1_56c.gif" width=188 height=34 align=Absmiddle>';
 
 var finding_x_intercept =
 'A point is on the x-axis if and only if its second coordinate y is zero.<br>  Therefore to find the x-intercepts of a '
 +'graph we let y = 0 and solve for x.';
  
 var finding_y_intercept =
 'A point is on the y-axis if and only if its first coordinate x is zero.<br>  Therefore to find the y-intercepts of a '
 +'graph we let x = 0 and solve for y.'; 
 
  var finding_x_intercept_function =
 'A point is on the x-axis if and only if its second coordinate y is zero.<br>  '
 +'Therefore to find the x-intercepts of a graph of a function f we let f(x) = 0 and solve for x.';
  
 var finding_y_intercept_function =
 'A point is on the y-axis if and only if its first coordinate x is zero.<br>  '
 +'Therefore to find the y-intercepts of a graph of a function f we let x = 0 '
 +'and solve for f(x).'; 
 
 var touch_equality_symbol =
 'Touch the equality symbols with your cursor to see why that equality is true.';
 var touch_parts =
 'Touch the equality symbols and other expressions with your cursor to see why that equality is true or how the expression'
+' is derived.';
 
 var square_root_of_a_product =
 'If a and b are non-negative real numbers, then '
 +'<IMG src="../../college_algebra/exercises/images_for_exercises/square_root_of_a_product.gif" alt="square root of a product is the product of the square roots" width=93 height=26 align=Absmiddle>.';
 

var conjugate_of_a_real_number =
 'A real number is its own conjugate<br> because a real number k can'
+' be written as <br>k + 0i whose conjugate is k - 0i = k.';

var complex_number_terminology =
 'The complex number i is sometimes called the complex unit or the imaginary unit.<br><br>'
 +'A number which can be written in the form 0 + bi where b is a non-zero real number, is called a pure '
 +'complex (or pure imaginary) number.<br>';

var complex_number_real =
 'Every real number a can be written as a complex number a + 0i.<br><br>'
 +'In particular the real number 0 can be written as a complex number 0 + 0i.<br>'
 +'A logical conclusion is that the set of real numbers is a subset of the complex numbers.';

var square_root_negative_work_hint =
 'When performing operations with square roots of negative numbers, begin by '
+'expressing all square roots in terms of i.'

var i_squared =
 'The definition of i is '
 +'<IMG src="../../image/square_root_of_negative_one_small.gif">.<br>'
 +'From this definition it follows that i<sup>2</sup> = -1.'; 

var computing_complex_product =
 'The product of two complex numbers is best computed as the product of two binomials.';

var radical_equation_one = 
 '<b class = highlight>When both sides of an equation are squared there is no assurance that the resulting equation will be '
 +'equivalent to the original equation.  Consequently it must be assumed that the resulting equation is not equivalent '
 +'to the original equation.</b>';
 
 var radical_equation_two =
 '<b class = highlight>When both sides of an equation are squared the solution set of the resulting equation contains the solution set '
 +'of the original equation.</span></b><br><br> '
 +'&nbsp;&nbsp;&nbsp;1.	This means that if both sides of an equation are squared and the resulting equation is solved, '
           +'those solutions are the only candidates as solutions to the original equation.<br>'
 +'&nbsp;&nbsp;&nbsp;2.	It also means that if both sides of an equation are squared and the resulting equation is solved, '
           +'some of those solutions may not be solutions to the original equation.';

var radical_equation_three =
 'To solve equations involving radicals, it is necessary to clear the equation of radicals. This is usually done by '
 +'squaring both sides of the equation.  The resulting equation may then be solved to obtain a solution set which '
 +'contains the original solution set. Therefore an integral part of the solution process is to test each of the '
 +'possible solutions in the original equation.';
          
var radical_equation_four = 
 'When squaring both sides of an equation is part of the solution process, testing all the possible solutions '
 +'in the original equation must also be a part of the solution process.';           



var rational_equation_one =
'<b class = highlight>When both sides of an equation are multiplied by an expression containing a variable there is no assurance that '
+'the resulting equation will be equivalent to the original.  Consequently it must be assumed that the resulting '
+'equation is not equivalent to the original equation.</b>';

var rational_equation_two =
'<b class = highlight>When both sides of an equation are multiplied by an expression containing a variable the solution set of the '
+'resulting equation contains the solution set of the original equation.</b><br><br>  '
+'&nbsp;&nbsp;&nbsp;1.	This means that if both sides of an equation are multiplied by an expression containing a '
+'variable and the resulting equation is solved, those solutions are the only candidates as solutions to the '
+'original equation. <br> '
+'&nbsp;&nbsp;&nbsp;2.	It also means that if both sides of an equation are multiplied by an expression containing '
+'a variable and the resulting equation is solved, some of those solutions may not be solutions to the original '
+'equation.';

var rational_equation_three =
'Therefore when multiplying both sides of an equation by an expression containing a variable is part of the '
+'solution process, testing all the possible solutions in the original equation must also be a part of the solution '
+'process.';

var rational_equation_four =
'To solve equations containing rational expressions, clear the equation of fractions by multiplying both sides of '
+'the equation by the LCD of all rational expressions. Then solve as usual.  Finally check each of these possible '
+'solutions in the original equation to determine its solution set.';

var long_division_natural_numbers =
 ' Long division is a process for calculating the quotient q and remainder r whose existence is assured by the '
 +'Division Algorithm. <br><br>Long division is also used to calculate the decimal equivalent of a fraction.';

var long_division_polynomials =
 ' Long division and Synthetic division are processes for calculating the quotient q and remainder r whose existence is assured by the '
 +'Division Algorithm for Polynomials.';

var remainder_theorem =
 'If a polynomial function f is divided by the polynomial function whose rule is <span class = "nobr">g(x) = x - k,</span> '
 +'then the remainder is <span class = "nobr">f(k).</span>';

var factor_theorem = 
'If g is a polynomial function whose rule is <span class = "nobr">g(x) = x &#8211; k</span> then g is a factor of a polynomial function f '
+'if and only if <span class = "nobr">f(k) = 0.</span>';

var factor_theorem_fact1 = 
'The above statement means:<br><br>'
+'<ol>'
+'<li>If <span class = "nobr">g(x) = x &#8211; k</span> and g is a factor of the polynomial function f, then <span class = "nobr">f(k) = 0.</span></li>'
+'<li>If <span class = "nobr">f(k) = 0</span> for a polynomial function f, then the function defined by <span class = "nobr">g(x) = x &#8211; k</span> is a factor of f.</li>'
+'</ol>';

var factor_theorem_fact2 =
 'The complex number k is a zero of the polynomial function f if and only if the function whose rule is '
 +'<span class = "nobr">g(x) = x &#8211; k</span> is a factor of f.';
 
  var possible_rational_zeros =
 'If <img src="../../image/p_over_q_large.gif" align="absmiddle"> is a rational zero of a polynomial function with integer coefficients,<br>'
 +' then the numerator p must be a divisor of the constant term and the denominator q must be a divisor of '
 +'the leading coeficient.';
 
 var fundamental_theorem_of_algebra =
 'If f is a polynomial function of degree <span class = "nobr">n > 0,</span> then f has at least one complex zero.';
 
 var complex_zeros1 = 
 'If f is a polynomial function of degree <span class = "nobr">n > 0</span> then f has exactly n complex zeros.';

var complex_zeros2 =
'Suppose f is a polynomial function with real coefficients. <br><br>If the complex number <span class = "nobr">a + bi</span> is a zero of '
+'the function f, then its conjugate <span class = "nobr">a - bi</span> is also a zero of the function f.<br>'
+'This fact is usually remembered by observing that complex zeros of polynomial functions occur in conjugate pairs.';

 var linear_and_quadratic_factors =
'Every polynomial of degree <span class = "nobr">n > 0</span> with real coefficients can be written as the product of linear and quadratic '
+'factors with real coefficients, where the quadratic factors have no linear factors with real coefficients.';
 
var prime_polynomials =
'Consider the set of all polynomials together with the usual operations of addition and multiplication.<br><br> '
+'In that set linear polynomials with real coefficients are prime polynomials. <br>'
+'In that set quadratic polynomials with '
+'no linear factors with real coefficients are prime polynomials.';


var prime_factorization_of_polynomials =
'In view of this observation the previous fact may be restated as follows: <br><br> '
 +'Every polynomial of degree <span class = "nobr">n > 0</span> with real coefficients can be written as the product of prime polynomials.';
 
var rational_function_domain_convention =
 'As with all functions the convention for the domain of a rational function is all real numbers for which '
 +'the rule is defined ( makes sense). Therefore the domain of a rational function is all real numbers except the '
 +'zeros of the denominator.';
 
 // Start SYSTEMS OF EQUATIONS AND INEQUALITIES  
 
var graph_of_linear_equation_in_two_variables =
'The solution set for a linear equation in two variables is the set of ordered pairs '
+'of numbers which make the equation true.  The graph of a linear equation in two variables is the line '
+'whose coordinates are solutions of the equation.  The graph is a picture of the solution set.';
  
var graph_of_system_of_two_linear_equations_two_variables =
'The solution of a system of two equations in two variables is the pair (or pairs) '
+'of numbers that make both equations true. The graph is therefore the point (or points) '
+'which is (are) on both lines.  Therefore the graph of the solution of a system of two '
+'equations in two variables is the point (or points) of intersection of the two lines.';
 
var system_of_equations_replacement =
 'In a system of linear equations, replacement of an equation with an equivalent equation '
 +'produces a system which is equivalent to the original system.<br><br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'
 +'<b class = "bold_blue">(A)</b> If the same expression is added to (or subtracted from) '
 +'both sides of an equation the resulting equation will be equivalent to the original '
 +'equation.<br><br>'
 +'&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;' 
 +'<b class = "bold_blue">(B)</b>If both sides of an equation are multiplied ( or divided) '
 +'by the same non-zero real number, the resulting equation is equivalent to the original '
 +'equation.';
 
 var system_of_equations_substitution =
 'In a system of linear equations, if the value of one of the variables is known, an '
 +'equivalent system is generated if that value is substituted into the equations.';

 var system_of_equations_linear_operation =
 'In a system of linear equations, if two equations are added (or subtracted) and one '
 +'(but not both) of the summand equations is replaced with the sum, the resulting system '
 +'of equations is equivalent to the original system of equations.';
 
 var determined_variable =
 'If a linear equation in a system of equations has only one variable, then the value of '
 +'that variable is determined for the system.';
 
 var graph_of_sum_of_equations =
 'If two linear equations in two variables are added, the graph of the third equation '
 +'(the sum) intersects the two original graphs at their intersection point. '
 +'Moreover, if the original two graphs are parallel, the third will be parallel to the '
 +'original graphs.';
 
 var basis_for_solution_methods =
 'Every method for solving a system of linear equations is based on the above methods '
 +'for generating equivalent systems of equations.'; 
 
  var solution_is_an_ordered_pair =
 'It is important to realize that a solution to a system of equations in two variables is an ordered '
 +'pair of real numbers.  It is not two numbers nor is it an ordinary set of two numbers.'; 
 
  var substitution_method_two_equations_two_variables =
 'The following method, called the <b class = "bold_blue">Substitution Method</b>, is suitable for solving a system '
 +'of two equations in two variables and some special larger systems.'
 +'<ol>'
 +'<li>Solve for one of the variables in one of the equations.</li>'
 +'<li>Substitute that value into the other equation to obtain an equation in one variable.</li>'
 +'<li>Solve that equation for the single variable.</li>'
 +'<li>Substitute that value into the equation in Step 1 and solve for the variable.</li>'
 +'<li>The obvious ordered pair is solution of the system.</li>'
 +'</ol>'; 
 
 
 
 //INDEX_MATRICES
 
  var representing_matrices =
 'In general we use capital letters to represent matrices and lower case letters to '
 +'represent entries of a matrix.  We use subscripts on the entries to indicate the row '
 +'and column which the entry occupies.<br><br>'
 +'<img class="graphicIndent" src="../image_matrix/matrix_notation1_small.gif" alt="matrix example small" >';
 
 var matrix_sum_different_order = 
 'The sum of two matrices with different orders is not defined.';
 
 var matrix_sum_opposite =
 'The sum of a matrix and its opposite is the zero matrix.';
 
 var matrix_addition_properties =
 'If A, B, and C are matrices with the same orders and both c and d are scalars, then'
 +'<blockquote>'
 +'<p>1. Matrix addition is <b class = "bold_blue">commutative</b><br><br>'
 +'<span class="nobr">A + B = B + A</span></p>'
 +'<p>2. Matrix addition is <b class = "bold_blue">associative</b><br>'
 +'<span class="nobr">A + (B + C) = (A + B) + C</span></p>'
 +'<p>3. Scalar Multiplication is <b class = "bold_blue">associative</b><br>'
 +'<span class="nobr">(cd)A = c(dA)</span></p>'
 +'<p>4. The number 1 is the <b class = "bold_blue">scalar identity</b><br>'
 +'<span class="nobr">1A = A</span></p>'
+'<p>5. Scalar multiplication <b class = "bold_blue">distributes</b> over matrix addition<br>'
 +'<span class="nobr">c(A + B) = cA + cB</span></p>'
+'<p>6. Scalar addition <b class = "bold_blue">distributes</b> over scalar multiplication<br>'
 +'<span class="nobr">(c + d)A = cA + dA</span></p>'
+'<p>7. The zero matrix <b><em>O</em></b> is the <b class = "bold_blue">additive identity</b><br>'
 +'<span class="nobr">A + <b><em>O</em></b> = <b><em>O</em></b> + A = A</span></p>'
+'</blockquote>'; 
 

 var matrix_multiplication_properties =
 'If A, B, and C are matricies and c is a scalar, then'
 +'<blockquote>'
+'<p>1. Matrix multiplication is <b class = "bold_blue">associative</b><br><br>'
+'<span class="nobr">A(BC) = (AB)C</span></p>'
+'<p>2. Matrix multiplication on the left <b class = "bold_blue">distributes</b> over matrix addition<br>'
+'<span class="nobr">A(B + C) = AB + AC</span></p>'
+'<p>3. Matrix multiplication on the right <b class = "bold_blue">distributes</b> over matrix addition<br>'
+'<span class="nobr">(A + B)C = AC + BC</span></p>'
+'<p>4. <b class = "bold_blue">Multiplicative Identity</b><br>'
+'If A is an n&times;n matrix and I<sub>n</sub> is the identity of order n, then<br>' 
+'<span class="nobr">I<sub>n</sub>A = AI<sub>n</sub> = A</span></p>'
+'<p>5. Scalar multiplication is <b class = "bold_blue">distributive</b> with '
+'respect to matrix multiplication<br>'
+'<span class="nobr">c(A + B) = cA + cB</span></p>' 
+'</blockquote>';
 
 var matrix_inner_product_remember =
 'An easy way to remember the definition of inner product is to observe that '
 +'the inner product is simply the sum of the products of corresponding entries.';
 
 var matrix_inner_product_example =
 'The following illustrates computing the inner product of a 1&times;3 row matrix with '
 +'a 3&times;1 column matrix.<br><br>'
 +'<img class="graphicIndent" src="../image_matrix/matrix_inner_product_example_small.gif" alt="matrix sum example">';
 

 var matrix_inner_product_scalar =
 'It is important to remember that the inner product of two matrices does not yield a matrix, '
 +'but yields a real number and those are called scalars in the context of matrices.';
 
 var matrix_product_dimension_factors =
  'The product of two matrices is defined only if the number of columns of the first '
  +'is equal to the number of rows of the second.  The order of the product is the '
  +'number of rows of the first times the number of columns of the second.  An easy '
  +'way to keep track of these conditions is to write the dimensions of the matrices'
  +' to be multiplied and then let the following diagram be your guide. <br><br>'
 +'<img class="graphicIndent" src="../image_matrix/matrix_product_dimension.gif" alt="dimensions">';

 var matrix_product_ij_entry =
  'The entry in the ij position of product matrix is the inner product of the '
  +'i<sup>th</sup> row of the first matrix and the j<sup>th</sup> column of the '
  +'second matrix.  For example, the entry in the 23 position (second row, third column)'
  +'is calculated by computing the inner product of the second row of the first '
  +'matrix times the third column of the second matrix.  Perhaps the following '
  +'colored diagram will help.'
  +'<img class="graphicIndent" src="../image_matrix/matrix_product_method.gif" alt="dimensions">';
  
var matrix_multiplication_schematic =
 'The following schematic diagram shows how to determine the rows and columns to use '
 +'in the various inner products when computing the product of two matrices. '
 +'Pay attention to the indices of the positions in the product matrix.<br><br>'
+'<img class="graphicIndent" src="../image_matrix/matrix_multiplication_schematic_small.gif" alt="matrix product schematic">';


var matrix_multiplication_explained =
 'The above definition is hard to understand because of the subscripting.  Matrix '
 +'multiplication is not as complicated as it looks.  Each entry in the product matrix '
 +'is the inner product of a row from the first matrix and a column from the second matrix.'
 +'  The index on the entry in the product tells you which row and column to use.  For '
 +'example to compute the entry in the 35 position '
 +'(3<sup>rd</sup> row 5<sup>th</sup> column), use the third row and fifth column.';

var matrix_multiplication_example =
 'A simple numeric example should cement your understanding of matrix multiplication.<br><br>'
 +'<img class="graphicIndent" src="../image_matrix/matrix_multiplication_example_small.gif" alt="matrix multiplication example">';



  var matrix_multiplication_not_commutative =
  'It is important to recognize and remember that matrix multiplication is not commutative.'
  +' Generally BA &ne; AB, although there are a few exceptions. Unless verified otherwise it '
  +'must be assumed that BA is not equal to AB. The following multiplications yield an example to show '
  +'that matrix multiplication is not commutative.';
  
  var matrix_multiplication_not_commutative_example =
  '<br><br><img class="graphicIndent" src="../image_matrix/matrix_multiplication_not_commutative_small.gif" alt="matrix multiplication is not commutative example.">';
  
  var matrix_example1 = 
  'When it is desirable to emphasize the notation used for individual entries we use '
  +'[a<sub>ij</sub>] instead of capital A to name the matrix.'
  +'<br><br><img class="graphicIndent" src="../image_matrix/matrix_notation2_small.gif" alt="matrix example small">'
  +'<br><br>and at other times we simply use a rectangular array to represent the matrix.'
  +'<br><br><img class="graphicIndent" src="../image_matrix/matrix_notation3_small.gif" alt="matrix example small">';
  
  var matrix_sum_example =
  'The following illustrates the calculations required to compute the sum of two '
  +'3&times;3 matrices.<br><br>'
  +'<img class="graphicIndent" src="../image_matrix/matrix_sum_example_small.gif" alt="matrix sum example">';
  
   var matrix_scalar_product_example =
  'The following illustrates the calculations required to compute a scalar product.<br><br>'
  +'<img class="graphicIndent" src="../image_matrix/matrix_scalar_product_example_small.gif" alt="matrix sum example">';
  
  var det_notation =
  'The name of the determinant function is <b class = "bold_blue">det</b>. Vertical bars '
  +'(such as used in absolute value) are also used to denote the determinant function. '
  +'For example if A is a matrix whose determinant is 5, we would write '
  +'<span class="nobr">det(A) = 5</span> or <span class="nobr">| A | = 5</span>.';
  
  var det_function_notation =
  'Because the determinant is a function we will emphasize function notation and in most '
  +'references we will use its name det.  '
  +'The normal function notation as used with the function named det is:<br><br><br><br> '
  +'<img class="graphicIndent" src="../image_matrix/det_function_notation_small.gif" alt="function notation for det"><br><br>';
  
  var det_function_notation_extension =
  'Historical use of notation, and sometimes convenience, requires a knowledge of and an '
  +'ability to use vertical bars to designate the determinant of a matrix. Therefore it '
  +'is common to encounter some notational variations.<br><br><br>'
  +'Instead of det(A) we may use |A|. <br>'
  +'Similar dual symbolism was encountered with the abs function and vertical bars for absolute value.<br><br>'
  +'When we want to emphasize the entries of the matrix we normally will write <br><br>'
  +'<img  class="graphicIndent"  src="../image_matrix/det_function_notation_example_small.gif" alt="det example"><br><br>'
  +'or we could use the vertical bar notation <br><br>'
  +'<img class="graphicIndent"  src="../image_matrix/det_vertical_bar_notation_example_small.gif" alt="det vertical bar example"><br><br>'
  +'In summary:<br><br>'
  +'<img class="graphicIndent" src="../image_matrix/det_function_notation_example_all_small.gif" alt="det all examples">';
  
  
  var det_function_general_comments =
  'Functions normally studied prior to this have had some common characteristics which are  '
  +'not shared by the det function.<br><br><br>'
  +' The domain of each of the earlier functions has been some subset of the real numbers.<br>'
  +' The domain of det is the set of square matrices.<br><br>'
  +'The rule for most of the earlier functions could be expressed as an equation '
  +'(or a couple of equations).<br>'
  +'The rule for the det function is a recursive rule and cannot be expressed as an equation. <br>'
  +'The meaning of recursive will become clear very shortly.';  
  
  var det_function_defined_recursively =
  'The following procedure will be used to describe the rule for the det function:'
  +'<ol>'
  +'<li> Describe the rule for the det of a 2&times;2 matrix in terms of its entries. </li>'
  +'<li> Describe the rule for the det of a 3&times;3 matrix in terms of the det of a 2&times;2 matrix.</li>'
  +'<li> Describe the rule for the det of a 4&times;4 matrix in terms of the det of a 3&times;3 matrix.</li>'
  +'<li> Describe the rule for the det of a 5&times;5 matrix in terms of the det of a 4&times;4 matrix.<br><br> and in general </li>'
  +'<li>Describe the rule for the det of a n&times;n matrix in terms of the det of a (n-1)&times;(n-1) matrix.</li>'
  +'</ol>'
  +'The technique illustrated with this definition; namely to define each item in terms '
  +'of its predessor in the sequence is called recursion and the definition is said to be '
  +'a recursive definition.';
 
var det_example_2by2 =
'<br><br><img class="graphicIndent" src="../image_matrix/det_example_2by2_small.gif" alt="det 2by2 example">';
  
  var det_example_ahat =
'<br><br><img class="graphicIndent" src="../image_matrix/det_example_ahat_small.gif" alt="det ahat example">';
  
  var det_example_cofactor =
'<br><br><img class="graphicIndent" src="../image_matrix/det_example_cofactor1_small.gif" alt="det cofactor1 example">'
+'<br><img class="graphicIndent" src="../image_matrix/det_example_cofactor2_small.gif" alt="det cofactor2 example">';

  var det_explanation_nbyn =
  'The rule may seem a bit confusing at first but is not really very complicated.<br><br> '
  +'Note that a<sub>11</sub> is the entry in the 11 position of the matrix and A<sub>11</sub> is its cofactor.<br>'
  +'Note that a<sub>12</sub> is the entry in the 12 position of the matrix and A<sub>12</sub> is its cofactor.<br>'
  +'and so on across the first row of the matrix A<br>'
  +'Note that a<sub>1n</sub> is the entry in the 1n position of the matrix and A<sub>1n</sub> is its cofactor.<br>'
  +'<br>So det(A) is just the sum of the products of each entry times its cofactor in the first row.';
  
  var det_amazing_row_col_expansion =
  'An amazing thing about the det function is that one can use any row to calculate '
  +'the determinant and the value will always be the same for a given matrix.<br><br><br>'
  +'The really amazing thing is that one can use any column to calculate det(A).';
  
  var det_row1_expansion_general_illustration_3by3 =
  'The computations here with a general 3&times;3 matrix should help understand the '
  +'rule for the function det. <br><br> The cofactor expansion along the first row will '
  +'be illustrated.  Pay close attention to the subscripts and exponents.  Subscripts for '
  +'an entry remain the same throughout the computations.  The subscripts always represent '
  +'the entry&prime;s position in the original matrix.  Note that the exponent on (-1) '
  +'is the sum of the indices of the matrix entry.'
  +'<img class="graphicIndent" src="../image_matrix/det_row1_expansion_general_illustration_3by3_small.gif" alt="general 3by3 cofactor expansion">';
  
  var det_row1_expansion_example =
  'This illustration uses cofactor expansion along Row 1.'
  +'<img class="graphicIndent" src="../image_matrix/det_row1_expansion_example_small.gif" alt="Row 1 cofactor expansion">';  
  
  var det_row2_expansion_example =
  'This illustration uses cofactor expansion along Row 2.'
  +'<img class="graphicIndent" src="../image_matrix/det_row2_expansion_example_small.gif" alt="Row 1 cofactor expansion">'
  +'<br><br>Notice that if an entry in the matrix is 0 then expansion along that row decreases the '
  +'computation.';  
  
  var det_row3_expansion_example =
  'This illustration uses cofactor expansion along Row 3.'
  +'<img class="graphicIndent" src="../image_matrix/det_row3_expansion_example_small.gif" alt="Row 1 cofactor expansion">';  
  
  var det_of_product =
  'If A and B are square matrices with the same dimension, then '
  +'<span class = "nobr"><b class = "bold_blue">det(AB) = det(A)det(B).</b></span>';
  
    var det_is_zero =
  'If A is a square matrix and <span class = "nobr">det(A) = 0,</span> then A does not '
  +'have an inverse.';

  var det_applications =
  'There are many other properties of the function det. A few of the many applications '
  +'of the determinant function are mentioned here.'
  +'<ul class="none">'
		+'<li>The function det can be used to solve systems of equations.  This generally involves Cramer&prime;s rule.</li>'
		+'<li>&nbsp;</li>'
		+'<li>If the vertices of a triangle are (x<sub>1</sub>,y<sub>1</sub>), '
		+'(x<sub>2</sub>,y<sub>2</sub>), (x<sub>3</sub>,y<sub>3</sub>) '
		+'then its area A is given by the formula:<br><br>'
		+'<img class="graphicIndent" src="../image_matrix/det_triangle_area_small.gif" alt="det area triangle">'
		+'</li>'
		+'<li>&nbsp;</li>'
		+'<li>Three points are colinear if  and only if the area of the triangle with the three points '
		+'as its vertices has area zero.  So a test for colinearity is to see if the equation '
		+'<br><br><img class="graphicIndent" src="../image_matrix/det_colinear_test_small.gif" alt="det colinear test">'
		+'<br>is true.</li>'
		+'<li>&nbsp;</li>'
		+'<li>The following det equation is the equation of the line through the points  '
		+'(x<sub>1</sub>,y<sub>1</sub>) and (x<sub>2</sub>,y<sub>2</sub>).<br><br>'
		+'<img class="graphicIndent" src="../image_matrix/det_line_equation_small.gif" alt="det line equation">'
		+'</li>'		
  +'</ul>';
  

  