Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 10 - 10.3 - The Inverse of a Square Matrix - 10.3 Exercises - Page 735: 44

Answer

$x=1; y= 7; z=-9$

Work Step by Step

A system of equations can be written in the form: $AX=B$ where $B= \begin{bmatrix} x \\ y \\ z \end{bmatrix}$ When there exists an inverse of a matrix, the following relationship is true: $A A^{-1} = I$ Thus, $X=A^{-1} B = \begin{bmatrix} 1&1&1 \\ 3 & 5 & 4 \\ 3&6& 5 \end{bmatrix} \begin{bmatrix} -1 \\ 2 \\ 0 \end{bmatrix} =\begin{bmatrix} 1 \\ 7 \\-9 \end{bmatrix}$ So, $X= \begin{bmatrix} x \\ y \\ z \end{bmatrix}=\begin{bmatrix}1 \\ 7 \\-9 \end{bmatrix}$ Therefore, $x=1; y= 7; z=-9$
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