Section 3'3 Graphing Linear Equations in Two Variables

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Section 3.3 Graphing Linear Equations in Two
Variables
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Example 1 Graph the solution set for x y 5

• (0, )
• (1, )
• (3, )
• (5, )

• (0, 5 )
• (1, 4 )
• (3, 2 )
• (5, 0 )

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Definition- Linear Equation

• Any equation that can be put into the form
• ax by c
• where a, b, and c are real numbers and a and b
  are both not 0, is called a linear equation in
  two variables.
• The graph of any equation in this form is a
  straight line.
• The form ax by c is called the standard form.

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To Graph a Straight Line

• Step1 Find any three ordered pairs. This can
  be done by using a convenient number for one
  variable and solving for the other variable.
• Step 2 Graph the three ordered pairs found in
  step 1.
• Step 3 Draw a straight line through the three
  points graphed in step 2.

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HW Page 183 10

• For the following equations complete the given
  ordered pairs and use the results to graph the
  equation.
• y -2x 1
• (0, ___)
• (-1, ___)
• (1, ___)

1
3
-1
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Graph y -2x 1

• (0,1)
• ( -1, 3)
• ( 1, -1)

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Complete the following ordered pairs for 3x - 4y
12

• (0, )
• ( , 0)
• ( , -2)
• (- 4, )

Do this for each ordered pair.
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Graph 3x - 4y 12

• (0, -3)
• ( 4 , 0)
• ( , -2)
• (- 4, -6)

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Graph the solution set ofy 4 0
(0, -4)
(2, -4)
(3, -4)
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Graphx 2
(2, 0)
(2, -4)
(2, 3)
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Getting Ready for Class

• Explain how you would go about graphing the line
  x y 5.
• When graphing straight lines, why is it a good
  idea to find three points when every straight
  line is determined by only two points?
• What kind of lines have vertical lines for
  graphs?
• What kind of equations have horizontal lines for
  graphs?

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HomeworkSection 3.3
Hello, again young Americans! 1- 43 odd Page 183
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1. Complete the given ordered pairs and use the
results to graph the solution set for the
equation. x y 4
(0, )
(2, )
( , 0)
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7. Complete the given ordered pairs and use the
results to graph the solution set for the
equation.
(-3, )
(0, )
(3, )
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13. Complete the given ordered pairs and use the
results to graph the solution set for the
equation.
(-2, )
(0, )
(2, )
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16. Complete the given ordered pairs and use the
results to graph the solution set for the
equation.
(-3, )
(0, )
(3, )
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18. Solve each equation for y. Then complete the
ordered pairs and use them to draw the graph.
(-1, )
(0, )
(1, )
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20. Solve each equation for y. Then complete the
ordered pairs and use them to draw the graph.
(0, )
(3, )
(6, )
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24. Find three solutions to each of the following
equations and then graph the solution set..
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26. Find three solutions to each of the following
equations and then graph the solution set..
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28. Find three solutions to each of the following
equations and then graph the solution set..
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