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: 23


One common solution $\Rightarrow$ $(2,1.25)$

Work Step by Step

We use the addition method below: We add the 2 equations: $5x-12y=-5$ $9x-16y=-2$ Multiply the first equation by $9$ and the second equation by $-5$ to cancel $x$: $+45x-108y=-45$ $\underline{-45x+80y=+10}$ $-28y=-35$ Solve for $y$: $y=\frac{-35}{-28}=\frac{5}{4}=1.25$ Substitute into any of the 2 equations and solve for x: $5x-12y=-5$ $5x-12(1.25)=-5$ $5x=-5+15$ $5x=10$ $x=\frac{10}{5}$ $x=2$
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