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: 43

Answer

$\left\{\left(8,2,0\right)\right\}$

Work Step by Step

We are given the system of equations: $\begin{cases} x-y=6\\ 2x-3z=16\\ 2y+z=4 \end{cases}$ Use the elimination method. Multiply the third equation by 3 and add it to the second equation to eliminate $z$: $\begin{cases} x-y=6\\ 2x-3z=16\\ 3(2y+z)=3(4) \end{cases}$ $\begin{cases} x-y=6\\ 2x-3z=16\\ 6y+3z=12 \end{cases}$ $\begin{cases} x-y=6\\ 2x-3z+6y+3z=16+12 \end{cases}$ $\begin{cases} x-y=6\\ 2x+6y=28 \end{cases}$ Multiply the first equation by 6 and add it to the second equation to eliminate $y$ and determine $x$: $\begin{cases} 6x-6y=6(6)\\ 2x+6y=28 \end{cases}$ $6x-6y+2x+6y=36+28$ $8x=64$ $x=8$ Determine $y$: $x-y=6$ $8-y=6$ $y=2$ Determine $z$: $2y+z=4$ $2(2)+z=4$ $4+z=4$ $z=0$ The solution set of the system is: $\left\{\left(8,2,0\right)\right\}$
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