Linear Algebra and Its Applications (5th Edition)

Published by Pearson
ISBN 10: 032198238X
ISBN 13: 978-0-32198-238-4

Chapter 3 - Determinants - 3.2 Exercises - Page 177: 22

Answer

The matrix is invertible.

Work Step by Step

We are given the matrix $\begin{bmatrix} 5 & 1 & -1 \\ 1 & -3 &-2 \\ 0 & 5 & 3\\ \end{bmatrix}$. To find the determinant: $\begin{vmatrix} 5 & 1 & -1 \\ 1 & -3 &-2 \\ 0 & 5 & 3\\ \end{vmatrix}$ = 5 $\begin{vmatrix} -3 & -2\\ 5 & 3\\ \end{vmatrix}$ -1 $\begin{vmatrix} 1 & -1\\ 5 & 3\\ \end{vmatrix}$ +0 $\begin{vmatrix} 1 & -1\\ -3 & -2\\ \end{vmatrix}$ = 5 (-9+10) - (3+5) +0 =5 - 8 = -3 Thus, since the determinant of the matrix does not equal zero, the matrix is invertible.
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