Elementary Linear Algebra 7th Edition

Published by Cengage Learning
ISBN 10: 1-13311-087-8
ISBN 13: 978-1-13311-087-3

Chapter 4 - Vector Spaces - Review Exercises - Page 221: 8

Answer

$x=\left( -\frac{2}{3},\frac{5}{3},\frac{1}{3}\right)$.

Work Step by Step

Assume that $x=(a,b,c)$ and $2 {u}+3 {x}=2 {v}-{w}$, then we have \begin{align*} &\Longrightarrow 2 (1,-1,2) +3 (a,b,c)=2(0,2,3)-(0,1,1)\\ &\Longrightarrow (2,-2,4) + (3a,3b,3c)=(0,4,6)+(0,-1,-1)\\ &\Longrightarrow (2,-2,4) + (3a,3b,3c)=(0,3,5)\\ &\Longrightarrow (3a,3b,3c)=(0,3,5)-(2,-2,4)\\ &\Longrightarrow (3a,3b,3c)=(-2,5,1). \end{align*} Hence, $a=-\frac{2}{3}$, $b=\frac{5}{3}$, $c=\frac{1}{3}$ and $x=\left( -\frac{2}{3},\frac{5}{3},\frac{1}{3}\right)$.
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