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: 60

Answer

$\begin{bmatrix} \frac{1}{x^2} &-\frac{x-1}{x^2}\\\frac{x-1}{x} &\frac{x-1}{x} \end{bmatrix} $ where $x\ne0, 1$

Work Step by Step

Step 1. Given the matrix: $\begin{array}( \\A= \\ \\ \end{array}\begin{bmatrix} x &1\\-x &\frac{1}{x-1} \end{bmatrix} $ Step 2. Use the formula in page 725 to get: $\begin{array}( \\A^{-1}=\frac{1}{\frac{x}{x-1}+x} \\ \\ \end{array}\begin{bmatrix} \frac{1}{x-1} &-1\\x &x \end{bmatrix} \begin{array}( \\=\frac{x-1}{x^2} \\ \\ \end{array}\begin{bmatrix} \frac{1}{x-1} &-1\\x &x \end{bmatrix}\begin{array}( \\= \\ \\ \end{array}\begin{bmatrix} \frac{1}{x^2} &-\frac{x-1}{x^2}\\\frac{x-1}{x} &\frac{x-1}{x} \end{bmatrix} $ Step 3. The inverse of the original matrix is: $\begin{bmatrix} \frac{1}{x^2} &-\frac{x-1}{x^2}\\\frac{x-1}{x} &\frac{x-1}{x} \end{bmatrix} $ and this inverse is not valid for $x=0, 1$
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