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 716: 53

Answer

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

Work Step by Step

We are given the system of equations: $\begin{cases} x+y-z=6\\ 3x-2y+z=-5\\ x+3y-2z=14 \end{cases}$ Use the elimination method. Add the second equation to the first equation; then multiply the second equation by 2 and add it to the third, to eliminate $z$: $\begin{cases} x+y-z+3x-2y+z=6-5\\ x+3y-2z+2(3x-2y+z)=14+2(-5) \end{cases}$ $\begin{cases} 4x-y=1\\ 7x-y=4 \end{cases}$ Multiply the first equation by -1 and add it to the second to eliminate $y$ and determine $x$: $\begin{cases} -4x+y=-1\\ 7x-y=4 \end{cases}$ $-4x+y+7x-y=-1+4$ $3x=3$ $x=1$ Determine $y$: $4x-y=1$ $4(1)-y=1$ $y=3$ Determine $z$: $x+y-z=6$ $1+3-z=6$ $z=-2$ The solution set of the system is: $\{(1,3,-2)\}$
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