Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 9 - Systems and Matrices - Chapter 9 Test Prep - Review Exercises - Page 951: 2

Answer

$\{(9,4)\}$

Work Step by Step

The system of equations are written as: $3x-5y=7 ~~~(1) \\ 2x+3y=30 ~~~(2)$ Equation -(1) yields: $x=\dfrac{7+5y}{3} ~~~~(3)$ Plug $x=\dfrac{7+5y}{3} $ into the second equation and then solve for $y$ to obtain: $2(\dfrac{7+5y}{3} )+3y=30 \\ \dfrac{19y}{3}=\dfrac{76}{3} \\ y=4$ Back substitution for $y=1$ in equation-3 to obtain: $x=\dfrac{7+5(4)}{3} =9$ Solution set: $\{(9,4)\}$
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