7.3 Linear Equations and Their Graphs

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7.3 Linear Equations and Their Graphs

• Objective
• To graph linear equations using the x and y
  intercepts
• To graph horizontal and vertical lines

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Linear Equations(Graphs are straight lines)

1. Equation is linear only if the each variable has
   an exponent of 1.
2. (exponent in denominator is not linear)
3. Products of variables not linear, ie (x)(y)

y 3x -7
y 2x 1
y x2 1
5y 14
xy 2
3
y
x - intercept
X
y - intercept
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• Graphing using Intercepts
• Let x0 and determine the y-intercept.
• Let y0 and determine the x-intercept
• Plot both points. Connect them with a line.

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Graph 4x 3y 12 using intercepts
Find x-intercept 4x 3(0) 12
Find y-intercept 4(0) 3y 12
4x 12
3y 12
x 3
y 4
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Graph 2x 3y 12 using intercepts
x y
0
0
6
7
Graph 3x 5y 15 using intercepts
x y
0
0
5
8
Graph 5x - 2y 10 using intercepts
x y
0
0
2
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Graph 2y 3x - 6 using intercepts
x y
0
0
2
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Horizontal and Vertical Lines

• The graph of y is HORIZONTAL
• The graph x is VERTICAL

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Graph 4y 16 using 3-points
x y
0
3
6
12
Graph 3x 18 using 3-points
x y
0
3
- 4
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Differences between graphing by using a table and
graphing by finding the x and y intercepts

• When graphing by a table you need to solve for y
  (Slope Intercept Form ymxb)
• When graphing by finding the x and y intercepts
  you do not have to solve for y (Standard Form Ax
  By C)

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AssignmentPage 316 16 40 (even)(use graph
paper)