Differential Equations and Linear Algebra (4th Edition)

Published by Pearson
ISBN 10: 0-32196-467-5
ISBN 13: 978-0-32196-467-0

Chapter 3 - Determinants - 3.3 Cofactor Expansions - Problems - Page 232: 12

Answer

$\det (A)=0$

Work Step by Step

We have the cofactor expansion theorem is: $\det (A)=a_{31}C_{31}+a_{32}C_{32}+a_{33}C_{33}$ with $C_{ij}=(-1)^{i+j}.M_{ij}$ to evaluate the given determinant of column 1: $\det (A)=3C_{31}-(-5)C_{32}+0C_{33}$ $\det (A)=3\begin{vmatrix} 2 & -3 \\ 0 & 5 \end{vmatrix}-(-5)\begin{vmatrix} 0 & -3 \\ -2 & 5 \end{vmatrix}+0\begin{vmatrix} 0 & 2 \\ -2 & 0 \end{vmatrix}$ Plug in the given values: $\det (A)=3.10+5.(-6)+0$ $\det (A)=30-30+0$ $\det (A)=0$
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