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: 16

Answer

One common solution $\Rightarrow$ $(8,-7)$

Work Step by Step

We use the addition method below. We add the 2 equations: $3x+2y=10$ $x+5y=-27$ Multiply the second equation $-3$ to cancel $x$: $+3x+2y=10$ $\underline{-3x-15y=81}$ $-13y=91$ Solve for for $y$ and simplify: $y=\frac{91}{-13}=-7$ Substitute into any of the 2 equations and solve for $x$: $3x-2y=10$ $3x+2(-7)=10$ $3x-14=10$ $3x=10+14$ $3x=24$ $x=\frac{24}{3}$ $x=8$
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