Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 10 - Section 10.5 - Inverses of Matrices and Matrix Questions - 10.5 Exercises - Page 733: 54

Answer

$\begin{bmatrix} -39/2 & -39\\15 & 30\\39/2 & 39 \end{bmatrix}$

Work Step by Step

Step 1. Represent the matrix equation in the form of $AX=B$, where $\begin{array}( \\A= \\ \\ \end{array}\begin{bmatrix} 0 & -2 &2\\3 & 1 & 3\\1&-2&3 \end{bmatrix}, \begin{array}( \\X= \\ \\ \end{array}\begin{bmatrix} x & u \\y & v\\z & w \end{bmatrix}, \begin{array}( \\B= \\ \\ \end{array}\begin{bmatrix} 3 & 6\\6 & 12\\0 & 0 \end{bmatrix}$ Step 2. Note that matrix A is the same as that of Exercise 23. Recall the answer to that question, we have: $\begin{array}( \\A^{-1}= \\ \\ \end{array}\begin{bmatrix} -9/2 & -1 &4\\3 & 1 & -3\\7/2&1&-3 \end{bmatrix}$ Step 3. Multiply the results from step 2 to the original equation, we have $A^{-1}AX=A^{-1}B$ and $X=A^{-1}B$, thus $\begin{array}( \\X= \\ \\ \end{array}\begin{bmatrix} -9/2 & -1 &4\\3 & 1 & -3\\7/2&1&-3 \end{bmatrix}\begin{bmatrix} 3 & 6\\6 & 12\\0 & 0 \end{bmatrix}\begin{array}( \\= \\ \\ \end{array}\begin{bmatrix} -39/2 & -39\\15 & 30\\39/2 & 39 \end{bmatrix}$ Step 4. The solutions to the original matrix equation are: $\begin{bmatrix} -39/2 & -39\\15 & 30\\39/2 & 39 \end{bmatrix}$
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