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: 15


One common solution $\Rightarrow$ $(-1,4)$

Work Step by Step

We will use the addition method to solve the equations. We add the 2 equations: $3x-2y=-11$ Multiply both sides by $-5$ to cancel $y$. $7x-10y=-47$ We get: $-15x+10y=55$ $\underline{+7x-10y=-47}$ $-8x=8$ Solving for $x$ and simplifying, we get: $x=\frac{-8}{8}=-1$ Now, substitute into any of the 2 equations and solve for $y$: $3x-2y=-11$ $3(-1)-2y=-11$ $-3-2y=-11$ $-2y=-11+3$ $-2y=-8$ $y=\frac{-8}{-2}$ $y=4$
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