Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 2 - Review Exercises - Page 174: 57

Answer

Point-slope form: $y-6=2(x-1)$ or $y-2=2(x+1)$. Slope-intercept form: $y=2x+4$.

Work Step by Step

If the line passes through a point $(x_1,y_1)$ and slope is $m$, then the point-slope form of the line's equation is. $\Rightarrow y-y_1=m(x-x_1)$.... (1) We are given: $\Rightarrow (x_1,y_1)=(1,6)$ $\Rightarrow (x_2,y_2)=(-1,2)$ Slope $m=\frac{change\;in\;y}{change\;in\;x}$ $\Rightarrow m=\frac{y_2-y_1}{x_2-x_1}$ Substitute all values. $\Rightarrow m=\frac{2-6}{-1-1}$ $\Rightarrow m=\frac{-4}{-2}$ $\Rightarrow m=2$ For the first point $(x_1,y_1)=(1,6)$ Substitute all values into the equation (1). $\Rightarrow y-(6)=(2)(x-(1))$ Simplify. $\Rightarrow y-6=2(x-1)$ The above equation is the point-slope form. For the second point $(x_2,y_2)=(-1,2)$ Substitute all values into the equation (1). $\Rightarrow y-(2)=(2)(x-(-1))$ Simplify. $\Rightarrow y-2=2(x+1)$ The above equation is the point-slope form. Now isolate $y$ to determine the slope-intercept form: $y=mx+b$. Use the distributive property. $\Rightarrow y-2=2x+2$ Add $2$ to both sides. $\Rightarrow y-2+2=2x+2+2$ Simplify. $\Rightarrow y=2x+4$ The above equation is the slope-intercept form.
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