Chapter 4'3: Quick Graphs Using Intercepts

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Chapter 4.3 Quick Graphs Using Intercepts

• Goals
• How to find the intercepts of the graphs of a
  linear equations
• How to use intercepts to sketch a quick graph of
  a line
• Why
• You can quickly sketch the graph of a linear
  equations by plotting its intercepts. The graph
  allows you to see relationships between the
  variables

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Finding the Intercepts of a Line

• Quick ways to find a line
• The graph of a linear equation, Ax By C, is a
  line
• Two points are all that are needed to determine a
  line

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• Consider the line given by Ax By C
• To find the x-intercept Let y 0 and
  solve for x in Ax C
• To find the y-intercept Let x 0 and
  solve for y in By C

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Heres An Example
Find the intercepts of x 5y 10

• X-INTERCEPT
• x 5y 10
• Original Equation
• x 5(0) 10
• Substitute 0 for y
• x 10
• Solve for x

• Y-INTECEPT
• x 5y 10
• Original Equation
• (0) 5y 10
• Substitute 0 for x
• y 2
• Solve for y

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Using Intercepts to Sketch a Quick Graph

• 3x 4y 12
• X-INTERCEPT
• 3x 4(0) 12
• 3x 12
• x 4
• (4,0)
• Y-INTERCEPT
• 3(0) 4y 12
• 4y 12
• y 3
• (0,3)