"Since the mathematicians have invaded the theory of relativity, I do not understand it myself any more."

-- Albert Einstein

Linear Equations and Intercepts

Section 3.3

Overview

• Recognizing Linear Equations• Intercepts• Using Intercepts for Graphs• Graphing Horizontal or Vertical Lines

Recognizing Linear Equations

• Standard form

Intercepts

• y-intercept• x-intercept

Using Intercepts for Graphs

• Finding x and y intercepts (p. 188)– To find y-intercept of an equation’s graph, replace x with 0

and solve for y– To find x-intercept of an equation’s graph, replace y with 0

and solve for x

Graphing Horizontal or Vertical Lines

• Standard Form– Ax + By = C

• What if A or B (but not both) were 0?– If A = 0,• then there is no x-term• and the graph is a horizontal line

– If B = 0,• then there is no y-term• and the graph is a vertical line

Graphing Horizontal or Vertical Lines

• Linear equations in one variable (p. 192)– Graph of y = b• is a horizontal line• With y-intercept (0, b)

– Graph of x = a• is a vertical line• With x-intercept (a, 0)

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-1-3 -2-4-5 1 32 4 5x

y