Algebra 2 (1st Edition)

Published by McDougal Littell
ISBN 10: 0618595414
ISBN 13: 978-0-61859-541-9

Chapter 3 Linear Systems and Matrices - 3.8 Use Inverse Matrices to Solve Linear Systems - 3.8 Exercises - Skill Practice - Page 215: 32

Answer

$x=-6, y=10$

Work Step by Step

Rewrite our system of equations in matrix form: $\begin{bmatrix} 2& 1\\ 2& 5 \end{bmatrix}.\begin{bmatrix} x\\ y \end{bmatrix}=\begin{bmatrix} -2\\ 38 \end{bmatrix}$ $\begin{bmatrix} x\\ y \end{bmatrix}=\frac{1}{10-2}\begin{bmatrix} 5 & -1\\ -2&2 \end{bmatrix}.\begin{bmatrix} -2\\ 38 \end{bmatrix}$ $\begin{bmatrix} x\\ y \end{bmatrix}=\frac{1}{8}\begin{bmatrix} -48\\ 80 \end{bmatrix}$ $\begin{bmatrix} x\\ y \end{bmatrix}=\begin{bmatrix} -6\\ 10 \end{bmatrix}$ Hence, $x=-6, y=10$
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