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: 19

Answer

$\det (A)=0$

Work Step by Step

We have the cofactor expansion theorem for the 1st row: $\det (A)=a_{11}C_{11}+a_{12}C_{12}+a_{13}C_{13}$ with $C_{ij}=(-1)^{i+j}.M_{ij}$ So, we get: $\det (A)=0C_{11}+(-2)C_{12}+1C_{13}$ $\det (A)=0\begin{vmatrix} 0 & -3 \\ 3 & 0 \end{vmatrix}+(-2)\begin{vmatrix} 2 & -3 \\ -1 & 0 \end{vmatrix}+1\begin{vmatrix} 2 & 0 \\ -1 & 3 \end{vmatrix}$ Plug in the given values: $\det (A)=0+2.(-3)+1.6$ $\det (A)=-6+6$ $\det (A)=0$
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