Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 11 - Systems of Equations and Inequalities - 11.1 Systems of Linear Equations: Substitution and Elimination - 11.1 Assess Your Understanding - Page 715: 26

Answer

$\left\{\left(-\dfrac{5}{3},1\right)\right\}$

Work Step by Step

We are given the system of equations: $\begin{cases} 2x+4y=\dfrac{2}{3}\\ 3x-5y=-10 \end{cases}$ Use the elimination method. Multiply the first equation by 5, multiply the second equation by 4, and add them to eliminate $y$ and determine $x$: $\begin{cases} 5(2x+4y)=5\left(\dfrac{2}{3}\right)\\ 4(3x-5y)=4(-10) \end{cases}$ $\begin{cases} 10x+20y=\dfrac{10}{3}\\ 12x-20y=-40 \end{cases}$ $10x+20y+12x-20y=\dfrac{10}{3}-40$ $22x=-\dfrac{110}{3}$ $x=-\dfrac{110}{66}$ $x=-\dfrac{5}{3}$ Determine $y$ using the second equation: $3x-5y=-10$ $3\left(-\dfrac{5}{3}\right)-5y=-10$ $-5-5y=-10$ $5y=5$ $y=1$ The solution set of the system is: $\left\{\left(-\dfrac{5}{3},1\right)\right\}$
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