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: 39


One common solution $\Rightarrow$ $(72,30)$

Work Step by Step

We use the addition method below: We add the two equations: $8x-5y=426$ $7x-2y=444$ Multiply the first equation by $7$ and the second equation by $-8$ to cancel $x$: $+56x-35y=2982$ $\underline{-56x+16y=-3552}$ $-19y=-570$ Solve for $y$: $y=\frac{-570}{-19}=30$ Substitute into any of the two equations and solve for $x$: $8x-5y=426$ $8x-5(30)=426$ $8x-150=426$ $8x=426+150$ $8x=576$ $x=\frac{576}{8}$ $x=72$
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