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: 44

Answer

$\left\{\left(-3,2,1\right)\right\}$

Work Step by Step

We are given the system of equations: $\begin{cases} 2x+y=-4\\ -2y+4z=0\\ 3x-2z=-11 \end{cases}$ Use the elimination method. Multiply the first equation by 2 and add it to the second equation to eliminate $y$: $\begin{cases} 2(2x+y)=2(-4)\\ -2y+4z=0\\ 3x-2z=-11 \end{cases}$ $\begin{cases} 4x+2y-2y+4z=-8+0\\ 3x-2z=-11 \end{cases}$ $\begin{cases} 4x+4z=-8\\ 3x-2z=-11 \end{cases}$ $\begin{cases} x+z=-2\\ 3x-2z=-11 \end{cases}$ Multiply the first equation by 2 and add it to the second equation to eliminate $z$ and determine $x$: $\begin{cases} 2x+2z=2(-2)\\ 3x-2z=-11 \end{cases}$ $2x+2z+3x-2z=-4-11$ $5x=-15$ $x=-3$ Determine $z$: $x+z=-2$ $-3+z=-2$ $z=1$ Determine $y$: $2x+y=-4$ $2(-3)+y=-4$ $-6+y=-4$ $y=2$ The solution set of the system is: $\left\{\left(-3,2,1\right)\right\}$
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