Elementary Technical Mathematics

Published by Brooks Cole
ISBN 10: 1285199197
ISBN 13: 978-1-28519-919-1

Chapter 9 - Section 9.2 - Solving Pairs of Linear Equations by Addition - Exercises - Page 332: 22


One common solution $\Rightarrow$ $(-4,0)$

Work Step by Step

We use the addition method below: We add the 2 equations: $5x-7y=-20$ $3x-19y=-12$ Multiply the first equation by $3$ and the second equation by $-5$ to cancel $x$: $+15x-21y=-60$ $\underline{-15x+95y=+60}$ $74y=0$ Solve for $y$: $y=\frac{0}{74}=0$ Substitute into any of the 2 equations and solve for x: $3x-19y=-12$ $3x-19(0)=-12$ $3x=-12$ $x=\frac{-12}{3}$ $x=-4$
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