Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 10 - Review - Exercises - Page 771: 66

Answer

$\begin{bmatrix}4&-8\\ -7&14 \end{bmatrix}$

Work Step by Step

Step 1. List the matrices needed: $\begin{array} \\A=\\ \end{array} \begin{bmatrix} 2&1\\ 3&2 \end{bmatrix}, \begin{array} \\B=\\ \end{array} \begin{bmatrix} 1&-2\\ -2&4 \end{bmatrix}$ Step 2. Solve X from the equation: $A^{-1}AX=X=A^{-1}B$ Step 3. Calculate $A^{-1}$ (use the formula from section 10.5): $\begin{array} \\A^{-1}=\\ \end{array} \frac{1}{2\times2-1\times3}\begin{bmatrix} 2&-1\\ -3&2 \end{bmatrix} =\begin{bmatrix} 2&-1\\ -3&2 \end{bmatrix}$ Step 4. Perform the operation: $\begin{array} \\A^{-1}B=\\ \end{array} \begin{bmatrix} 2&-1\\ -3&2 \end{bmatrix} \begin{bmatrix} 1&-2\\ -2&4 \end{bmatrix} =\begin{bmatrix}4&-8\\ -7&14 \end{bmatrix}$ Step 5. Write the solution: $\begin{array} \\X=\\ \end{array} \begin{bmatrix}4&-8\\ -7&14 \end{bmatrix}$
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