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 - 3.5 Chapter Review - Additional Problems - Page 243: 4

Answer

22

Work Step by Step

(a) $|A|=\begin{vmatrix} -1 & 4 & 1\\ 0 & 2 & 2\\ 2 & 2 & -3 \end{vmatrix}=(-1).2.(-3)+4.2.2+1.0.2-1.2.2-(-1).2.2-0.4.(-3)=22$ b) Using elementary row operations: $|A|=\begin{vmatrix} -1 & 4 & 1\\ 0 & 2 & 2\\ 2 & 2 & -3 \end{vmatrix} \approx \begin{vmatrix} -1 & 4 & 1\\ 0 & 2 & 2\\ 0 & 10 & -1 \end{vmatrix} \approx \begin{vmatrix} -1 & 4 & 1\\ 0 & 2 & 2\\ 0 &0 & -11 \end{vmatrix}=22$ c) Using the Cofactor Expansion Theorem $|A|=A_{11}C_{11}+A_{12}C_{12}+A_{13}C_{13}=-1.(-10)-4.(-4)+1.(-4)=22$
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