Elementary Linear Algebra 7th Edition

Published by Cengage Learning
ISBN 10: 1-13311-087-8
ISBN 13: 978-1-13311-087-3

Chapter 2 - Matrices - 2.1 Operations with Matrices - 2.1 Exercises - Page 48: 16

Answer

$$x=1, \quad y=\frac{3}{2}, \quad z=-\frac{1}{4}, \quad w=-1.$$

Work Step by Step

We have \begin{align*} &\left[\begin{array}{rrr}{w} & {x} \\ {y} & {x} \end{array}\right]=\left[\begin{array}{rrr}{-4} & {3} \\ {2} & {-1} \end{array}\right]+2\left[\begin{array}{rrr}{y} & {w} \\ {z} & {x} \end{array}\right]\\ \Longrightarrow & \left[\begin{array}{rrr}{w} & {x} \\ {y} & {x} \end{array}\right]=\left[\begin{array}{rrr}{-4} & {3} \\ {2} & {-1} \end{array}\right]+\left[\begin{array}{rrr}{2y} & {2w} \\ {2z} & {2x} \end{array}\right]\\ \Longrightarrow & \left[\begin{array}{rrr}{w} & {x} \\ {y} & {x} \end{array}\right]=\left[\begin{array}{rrr}{-4+2y} & {3+2w} \\ {2+2z} & {-1+2x} \end{array}\right]\\ \end{align*} By comparing the corresponding entries of the matrices in both sides of the above equation, we get the following system of equations \begin{align*} w&=-4+2y\\ x&=3+2w\\ y&=2+2z\\ x&=-1+2x. \end{align*} From which, we have the solution $$x=1, \quad y=\frac{3}{2}, \quad z=-\frac{1}{4}, \quad w=-1.$$
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