Differential Equations and Linear Algebra (4th Edition)

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

Chapter 7 - Eigenvalues and Eigenvectors - 7.1 The Eigenvalue/Eigenvector Problem - Problems - Page 445: 46

Answer

See below

Work Step by Step

1. Find eigenvalues: (A-$\lambda$I)$\vec{V}$=$\vec{0}$ $\begin{bmatrix} 5-\lambda & 34 & -41 \\ 4 & 17-\lambda & -23 \\ 5 & 24 & -31-\lambda \end{bmatrix}\begin{bmatrix} v_1\\ v_2 \\ v_3 \end{bmatrix}=\begin{bmatrix} 0\\ 0 \\ 0 \end{bmatrix}$ $\begin{bmatrix} 5-\lambda & 34 & -41 \\ 4 & 17-\lambda & -23 \\ 5 & 24 & -31-\lambda \end{bmatrix}=0$ $(\lambda+2)^2(\lambda+5)=0$ $\lambda_1=\lambda_2=-2, \lambda_3=-5$ 2. Find eigenvectors: For $\lambda=-2$ let $B=A-\lambda_1I$ $B=\begin{bmatrix} 7 & 34 & -41 \\ 4 & 19 & -23 \\ 5 & 24 & -29 \end{bmatrix}=\begin{bmatrix} 0\\ 0 \\ 0 \end{bmatrix} $ Let $r,s$ be free variables. $\vec{V}=r(1,1,1)+s(1,1,1)\\ E_1=\{(1,1,1);(1,1,1)\} \\ \rightarrow dim(E_2)=2$ For $\lambda=-5$ let $B=A-\lambda_1I$ $B=\begin{bmatrix} 10 & 34 & -41 \\ 4 & 22 & -23 \\ 5 & 24 & -16 \end{bmatrix}=\begin{bmatrix} 0\\ 0 \end{bmatrix} $ Let $t$ be a free variable. $\vec{V}=t(20,11,14)\\ E_2=\{(20,11,14)\} \\ \rightarrow dim(E_2)=1$
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