Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 8 - Cumulative Review Exercises - Page 660: 2

Answer

$\{(-5,2)\}$.

Work Step by Step

We will use the Elimination Method to solve the given system of equations: $\Rightarrow 3x+4y=-7$ ...... (1) $\Rightarrow x-2y=-9$ ...... (2) Multiply equation (2) by $-3$. $\Rightarrow -3(x-2y)=-3(-9)$ Simplify. $\Rightarrow -3x+6y=27$ ...... (3) Add equation (1) and (3). $\Rightarrow 3x+4y-3x+6y=-7+27$ Simplify. $\Rightarrow 10y=20$ Divide both sides by $10$. $\Rightarrow \frac{10y}{10}=\frac{20}{10}$ Simplify. $\Rightarrow y=2$ Substitute the value of $y$ into equation (2). $\Rightarrow x-2(2)=-9$ Simplify. $\Rightarrow x-4=-9$ Add both sides $4$. $\Rightarrow x-4+4=-9+4$ Simplify. $\Rightarrow x=-5$ Hence, the solution set is $\{(-5,2)\}$.
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