College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 6 - Summary, Review, and Test - Review Exercises - Page 657: 55

Answer

$x=-3$ $y=2$ $z=1$

Work Step by Step

First we have to compute the determinants $D,D_x,D_y,D_z$: $D=\begin{vmatrix}2&1&0\\0&1&-2\\3&0&-2\end{vmatrix}=-4-6+0-0-0-0=-10$ $D_x=\begin{vmatrix}2&1&0\\0&1&-2\\3&0&-2\end{vmatrix}=8+22+0-0-0-0+30$ $D_y=\begin{vmatrix}2&1&0\\-4&0&-11\\3&0&-2\end{vmatrix}=0+24+0-0-44-0=-20$ $D_z=\begin{vmatrix}2&1&0\\0&1&-2\\-4&0&-11\end{vmatrix}=-22+0+0+12-0-0=-10$ We use Cramer's Rule to determine the solutions of the system: $x=\dfrac{D_x}{D}=\dfrac{30}{-10}=-3$ $y=\dfrac{D_y}{D}=\dfrac{-20}{-10}=2$ $z=\dfrac{D_z}{D}=\dfrac{-10}{-10}=1$ The solution is: $x=-3$ $y=2$ $z=1$
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