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: 45

Answer

$x=-20, y=10, z=16$

Work Step by Step

Step 1. Write the original system of equations in matrix form $AX=B$: $\begin{bmatrix} 0 & -2 & 2\\3 & 1 & 3\\1 & -2 & 3 \end{bmatrix} \begin{bmatrix} x\\y\\z \end{bmatrix}\begin{array}( \\= \\ \\ \end{array} \begin{bmatrix} 12\\-2\\8 \end{bmatrix}$ Step 2. Note that matrix A is the same as in 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. Use the formula $X=A^{-1}B$, we get the solutions as: $\begin{bmatrix} -9/2 & -1 & 4\\3 & 1 & -3\\7/2 & 1 & -3 \end{bmatrix} \begin{bmatrix} 12\\-2\\8 \end{bmatrix} \begin{array}(\\=\\ \\ \end{array} \begin{bmatrix} -20\\10\\16 \end{bmatrix}$ Step 4. Conclusion: the solutions for the system of equations are $x=-20, y=10, z=16$
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