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 444: 26

Answer

$\lambda_1=1$ $\vec{V}=(1,0,-1)r$ $\lambda_2 =2$ $\vec{V}=(-0.5,1,0)v + (0.5,0,1)w$

Work Step by Step

1. eigenvalues: (A-$\lambda$I)$\vec{V}$=$\vec{0}$ $\begin{bmatrix} 0-\lambda &1 &-1 \\ 0& 2-\lambda&0\\ 2&-1 &3-\lambda \end{bmatrix}\begin{bmatrix} v_1\\ v_2\\ v_3 \end{bmatrix}=\begin{bmatrix} 0\\ 0\\ 0 \end{bmatrix}$ $\begin{vmatrix} 0-\lambda &1 &-1 \\ 0& 2-\lambda&0\\ 2&-1 &3-\lambda \end{vmatrix}=0$ $\lambda_1=1$ $\lambda_2 =2$ $\lambda_3 =2$ =============================== 2. eigenvectors $\lambda_1=1$ let $B=A-\lambda_1I$ $B= \begin{bmatrix} 0-\lambda_1 &1 &-1 \\ 0& 2-\lambda_1&0\\ 2&-1 &3-\lambda_1 \end{bmatrix}$ = $\begin{bmatrix} -1&1&-1 \\ 0 &1 &0\\ 2&-1 &2 \end{bmatrix}$ Then, $B\vec{V}$=$\vec{0}$ Use reduced row echelon form $[B|\vec{0}]$= \[ \left(\begin{array}{@{}ccc|c@{}} 1 & 0 & 1 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 0 & 0 \end{array}\right) \] let $r$ is a free variable. $\vec{V}=(1,0,-1)r$ ============================= $\lambda_2=2$ let $B=A-\lambda_2I$ $B= \begin{bmatrix} 0-\lambda_2 &1 &-1 \\ 0& 2-\lambda_2&0\\ 2&-1 &3-\lambda_2 \end{bmatrix}$ = $\begin{bmatrix} -2&1&-1 \\ 0 &0 &0\\ 2&-1 &1 \end{bmatrix}$ Then, $B\vec{V}$=$\vec{0}$ Use reduced row echelon form $[B|\vec{0}]$= \[ \left(\begin{array}{@{}ccc|c@{}} 1 & -0.5 & 0.5 & 0 \\ 0 & 0 & 0& 0 \\ 0 & 0 & 0 & 0 \end{array}\right) \] let $v$and $w$ are a free variable. $\vec{V}=(-0.5,1,0)v + (0.5,0,1)w$
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