Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 3 - Test - Page 251: 20

Answer

$(x,y,z)=(4,-3,3)$

Work Step by Step

Formula to determine the determinant, $D$ of a $3 \times 3$ matrix is: $D=\begin{vmatrix}a&b&c\\d&e&f\\g&h&i\end{vmatrix}=a \begin{vmatrix}e&f\\h&i\end{vmatrix}-b \begin{vmatrix}d&f\\g&i\end{vmatrix}+c \begin{vmatrix}d&e\\g&h\end{vmatrix}$ Need to apply Cramer's Rule. $x=\dfrac{D_x}{D};y=\dfrac{D_y}{D}; z=\dfrac{D_z}{D}$ Now $D=\begin{vmatrix}2&3&1\\3&3&-1\\1&-2&-3\end{vmatrix}=-7$; and $D_x=\begin{vmatrix}2&3&1\\0&3&-1\\1&-2&-3\end{vmatrix}=-28$; $D_y=\begin{vmatrix}2&2&1\\3&0&-1\\1&1&-3\end{vmatrix}=21$ $D_z=\begin{vmatrix}2&3&2\\3&3&0\\1&-2&1\end{vmatrix}=-21$ Thus, $x=\dfrac{-28}{-7}=4;y=\dfrac{21}{-7}=-3; z=\dfrac{-21}{-7}=3$ Hence, $(x,y,z)=(4,-3,3)$
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