College Algebra (6th Edition)

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

Chapter 6 - Matrices and Determinants - Exercise Set 6.5 - Page 652: 35

Answer

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

Work Step by Step

First we have to compute the determinants $D,D_x,D_y,D_z$: $D=\begin{vmatrix}1&0&2\\0&2&-1\\2&3&0\end{vmatrix}=1(0+3)-0(0+2)+2(0-4)=-5$ $D_x=\begin{vmatrix}4&0&2\\5&2&-1\\13&3&0\end{vmatrix}=4(0+3)-0(0+13)+2(15-26)=-10$ $D_y=\begin{vmatrix}1&4&2\\0&5&-1\\2&13&0\end{vmatrix}=1(0+13)-4(0+2)+2(0-10)=-15$ $D_z=\begin{vmatrix}1&0&4\\0&2&5\\2&3&13\end{vmatrix}=1(26-15)-0(0-10)+4(0-4)=-5$ We use Cramer's Rule to determine the solutions of the system: $x=\dfrac{D_x}{D}=\dfrac{-10}{-5}=2$ $y=\dfrac{D_y}{D}=\dfrac{-15}{-5}=3$ $z=\dfrac{D_z}{D}=\dfrac{-5}{-5}=1$ The solution is: $x=2$ $y=3$ $z=1$
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