Notes
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Outline
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Algebra Review
 Basic Graphing Techniques
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Graphing Equations
  • The graph of an equation consists of all the points which satisfy or solve the equation.
      • Solve the equation to find the points, then plot the points.
  • These points are called coordinates.
  • Each point (coordinate) consists of one value for y and one value for x, and is written as the ordered pair  (x, y).
  • The values of (x, y) solve the equation   y = x + c,
      • where  c  represents a constant value
  • The coordinates are ordered pairs of real numbers.
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Variables of an Equation
  • x and y are most commonly used as variables in an equation
  • Variables are placeholders for values
  • Variable y is dependent on the variable x
  • The independent variable, x, is plotted along the horizontal axis (x axis)
  • The dependent variable, y, is plotted along the vertical axis (y axis)
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Solve for Ordered Pairs
  • Consider the linear equation    y = x + 2
  • The y value is dependent on the value of x
  • Find ordered pairs by assigning any value to x
  •      Let x = 0  and solve for y to find (0, y)
    • y = 0 + 2    or    y = 2     The ordered pair is (0, 2)
  •      Let x = 1  and solve again for y to find (1, y)
    • y = 1 + 2    or    y = 3     The ordered pair is (1, 3)
  •      Let x = -2  and solve again for y to find (-2, y)
    • y = -2 + 2   or   y = 0      The ordered pair is (-2, 0)
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Table and Graph for Ordered Pairs
  • Solutions for y = x + 2 put in a table form
  •             x      y
  •             0      2
  •             1      3
  •            -2      0
  •            -1      1
  •    Graph of   y = x + 2


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Types of Graphs
  • y = 2x + 3 is the graph of a straight line
  • y = 2x2 + 3 is the graph of a curved line called a parabola
  • y2 = 2x2 + 3 and y = x3 + 3 are also curved line graphs
  • Graphs are drawn by solving the equations and plotting the ordered pairs.
  • Draw the simplest graph you can to connect all the points.