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: 19

Answer

See below

Work Step by Step

1. Find eigenvalues: (A-$\lambda$I)$\vec{V}$=$\vec{0}$ $\begin{bmatrix} 2-\lambda & 3 \\ -3 & 2-\lambda \end{bmatrix}\begin{bmatrix} v_1\\ v_2 \end{bmatrix}=\begin{bmatrix} 0\\ 0 \end{bmatrix}$ $\begin{bmatrix} 2-\lambda & 3 \\ -3 & 2-\lambda \end{bmatrix}=0$ $\left (2- \lambda \right )\left (- \lambda +2 \right )+9=0$ $\lambda^2-4\lambda +13=0$ $\lambda_1=2+3i$ and $\lambda_2=2-3i$ 2. Find eigenvectors: For $\lambda_1=2+3i$ let $B=A-\lambda_1I$ $B=\begin{bmatrix} 2-\lambda & 3 \\ -3 & 2-\lambda \end{bmatrix}= \begin{bmatrix} -3i & 3 \\ -3 & -3i \end{bmatrix}$ Then, $B\vec{V}$=$\vec{0}$ Use reduced row echelon form $[B|\vec{0}]$= \[ \left(\begin{array}{@{}cc|c@{}} -i & 1 & 0 \\ 0 & 0& 0 \\ \end{array}\right) \] let $r$ is a free variable. Then $(-i)x_1=x_2 = r$ $\vec{V}=(1,-i)r$ For $\lambda_1=2-3i$ let $B=A-\lambda_1I$ $B=\begin{bmatrix} 2-\lambda & 3 \\ -3 & 2-\lambda \end{bmatrix}= \begin{bmatrix} 3i & 3 \\ -3 & 3i \end{bmatrix}$ Then, $B\vec{V}$=$\vec{0}$ Use reduced row echelon form $[B|\vec{0}]$= \[ \left(\begin{array}{@{}cc|c@{}} i & 1 & 0 \\ 0 & 0& 0 \\ \end{array}\right) \] let $r$ is a free variable. Then $(i)x_1=x_2 = r$ $\vec{V}=(1,i)r$
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