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: 30


One common solution $\Rightarrow$ $(-3,0)$

Work Step by Step

We use the addition method below: We add the 2 equations: $3x-7y=-9$ $2x+14y=-6$ Multiply both sides of the first equation by 2 to cancel $y$. $6x-14y=-18$ $\underline{2x+14y=-6}$ $8x=-24$ Solve for $x$: $x=\frac{-24}{8}=-3$ Substitute into any of the two equations and solve for $y$: $3(-3)-7y=-9$ $-9-7y=-9$ $7y=-9+9$ $7y=0$ $y=\frac{0}{7}$ $y=0$
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