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: 16

Answer

1. $\lambda_1= 4 + 3i$ and $\lambda_2= 4 - 3i$ 2. $\vec{V}=(−(0.5+0.5i),1)r$ $\vec{V}=(−(0.5-0.5i),1)r$

Work Step by Step

1. Find eigenvalues: (A-$\lambda$I)$\vec{V}$=$\vec{0}$ $\begin{bmatrix} 7-\lambda &3 \\ -6& 1-\lambda \end{bmatrix}\begin{bmatrix} v_1\\ v_2 \end{bmatrix}=\begin{bmatrix} 0\\ 0 \end{bmatrix}$ $\begin{vmatrix} 7-\lambda &3 \\ -6& 1-\lambda \end{vmatrix}=0$ $\lambda_1= 4 + 3i$ and $\lambda_2= 4 - 3i$ 2. $\lambda_1= 4 + 3i$ let $B=A-\lambda_1I$ $B= \begin{bmatrix} 7-\lambda_1 &3 \\ -6& 1-\lambda_1 \end{bmatrix}$ = $\begin{bmatrix} 3 - 3i &3 \\ -6&-3 - 3i \end{bmatrix}$ Then, $B\vec{V}$=$\vec{0}$ Use reduced row echelon form $[B|\vec{0}]$= \[ \left(\begin{array}{@{}cc|c@{}} 1 & 0.5 + 0.5i & 0 \\ 0 & 0 & 0 \\ \end{array}\right) \] let $r$ is a free variable. Then $x_1=-(0.5 + 0.5i)x_2 = -(0.5 + 0.5i) r$ $\vec{V}=(−(0.5+0.5i),1)r$ ======================== $\lambda_2= 4 - 3i$ let $B=A-\lambda_2I$ $B= \begin{bmatrix} 7-\lambda_2 &3 \\ -6& 1-\lambda_2 \end{bmatrix}$ = $\begin{bmatrix} 3 + 3i &3 \\ -6&-3 + 3i \end{bmatrix}$ Then, $B\vec{V}$=$\vec{0}$ Use reduced row echelon form $[B|\vec{0}]$= \[ \left(\begin{array}{@{}cc|c@{}} 1 & 0.5 - 0.5i & 0 \\ 0 & 0 & 0 \\ \end{array}\right) \] let $r$ is a free variable. Then $x_1=-(0.5 - 0.5i)x_2 = -(0.5 - 0.5i) r$ $\vec{V}=(−(0.5-0.5i),1)r$
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