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 - 7.6 Jordan Canonical Forms - Problems - Page 487: 37

Answer

See below

Work Step by Step

1. Find eigenvalues: (A-$\lambda$I)$\vec{V}$=$\vec{0}$ $\begin{bmatrix} -3-\lambda & -2 \\ 2 & 1-\lambda \end{bmatrix}\begin{bmatrix} v_1\\ v_2 \end{bmatrix}=\begin{bmatrix} 0\\ 0 \end{bmatrix}$ $\begin{bmatrix} -3-\lambda & -2 \\ 2 & 1-\lambda \end{bmatrix}=0$ $(\lambda+1)^2=0$ $\lambda_1=\lambda_2=-1$ 2. Find eigenvectors: For $\lambda=-1$ let $B=A-\lambda_1I$ $B=\begin{bmatrix} -3-\lambda & -2 \\ 2 & 1-\lambda \end{bmatrix}=\begin{bmatrix} -2& -2 \\ 2 & 0 \end{bmatrix}=\begin{bmatrix} 0\\ 0 \end{bmatrix} $ Let $r,s$ be free variables. $\vec{V}=r(-2,2)+s(1,0)\\ E_1=\{(-2,2);(1,0)\} \\ \rightarrow dim(E_2)=2$ Hence, $S=\begin{bmatrix} -2 & 2\\ 1 & 0 \end{bmatrix} $ We have $x=Sy \rightarrow x'=Ax \rightarrow y'=\begin{bmatrix} -1 & 1 \\ 0 & -1 \end{bmatrix}y $ then $y_1=c_2e^{-t}+c_1te^{-t}\\ y_2=c_1e^{-t}$ Hence, $x(t)=S.y(t)=\begin{bmatrix} -2 & 1\\ 2 & 0 \end{bmatrix} \begin{bmatrix} c_1te^{-t}+c_2e^{-t}\\ c_1e^{-t}\end{bmatrix} \\ =\begin{bmatrix} e^{-t}(-2c_2-2c_1t+c_1)\\ e^{-t}(2c_2+2c_1t)\end{bmatrix} $
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