1.4 Equations of Lines and Modeling

  • Determine equations of lines.

  • Given the equations of two lines, determine whether their graphs are parallel or perpendicular.

  • Model a set of data with a linear function.

Slope–Intercept Equations of Lines

In Section 1.3, we developed the slope–intercept equation y=mx+b, or f(x)=mx+b. If we know the slope and the y-intercept of a line, we can find an equation of the line using the slope–intercept equation.

Example 1

A line has slope 79 and y-intercept (0,16). Find an equation of the line.


We use the slope–intercept equation and substitute 79 for m and 16 for b:

y=mx+by=79x+16, orf(x)=79x+16.

Now Try Exercise 7.

Example 2

A line has slope 23 and contains the point (−3, 6). Find an equation ...

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