Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 8 - Mid-Chapter Check Point - Page 920: 10

Answer

$ X=\left[ \begin{matrix} 0.5 & 0.5 \\ -3 & 0.5 \\ \end{matrix} \right]$

Work Step by Step

Given $ C=\left[ \begin{matrix} -1 & 0 \\ 0 & 1 \\ \end{matrix} \right]$ and $ B=\left[ \begin{matrix} 4 & 1 \\ -6 & -2 \\ \end{matrix} \right]$. Since both matrices are $2\times 2$, the matrix operations are valid. Now $\begin{align} & 2X-3C=B \\ & 2X=B+3C \\ & X=\frac{B+3C}{2} \end{align}$ Substitute the corresponding values to get: $\begin{align} & X=\frac{\left[ \begin{matrix} 4 & 1 \\ -6 & -2 \\ \end{matrix} \right]+3\left[ \begin{matrix} -1 & 0 \\ 0 & 1 \\ \end{matrix} \right]}{2}=\frac{\left[ \begin{matrix} 4 & 1 \\ -6 & -2 \\ \end{matrix} \right]+\left[ \begin{matrix} -3 & 0 \\ 0 & 3 \\ \end{matrix} \right]}{2} \\ & =\frac{\left[ \begin{matrix} 4-3 & 1+0 \\ -6+0 & -2+3 \\ \end{matrix} \right]}{2}=\frac{\left[ \begin{matrix} 1 & 1 \\ -6 & 1 \\ \end{matrix} \right]}{2} \\ & =\frac{1}{2}\left[ \begin{matrix} 1 & 1 \\ -6 & 1 \\ \end{matrix} \right] \\ & =\left[ \begin{matrix} \frac{1}{2} & \frac{1}{2} \\ \frac{-6}{2} & \frac{1}{2} \\ \end{matrix} \right] \end{align}$ Therefore, $ X=\left[ \begin{matrix} 0.5 & 0.5 \\ -3 & 0.5 \\ \end{matrix} \right]$
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