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 - 7.7 Chapter Review - Additional Problems - Page 490: 11

Answer

See below

Work Step by Step

1. Find eigenvalues: (A-$\lambda$I)$\vec{V}$=$\vec{0}$ $\begin{bmatrix} 5-\lambda & 8 & 16 \\ 4 & 1-\lambda & 8\\ -4 & -4 & -11 - \lambda\end{bmatrix} \begin{bmatrix} v_1\\ v_2 \\ v_3\end{bmatrix}=\begin{bmatrix} 0\\ 0 \\0 \end{bmatrix}$ $\begin{bmatrix} 5-\lambda & 8 & 16 \\ 4 & 1-\lambda & 8\\ -4 & -4 & -11 - \lambda\end{bmatrix} =0$ $\lambda_1=1, \lambda_2=-3$ 2. Find eigenvectors: For $\lambda=1$ let $B=A-\lambda_1I$ $B=\begin{bmatrix} 5-\lambda & 8 & 16 \\ 4 & 1-\lambda & 8\\ -4 & -4 & -11 - \lambda\end{bmatrix} =\begin{bmatrix} 4 & 8 & 16\\ 4 & 0 & 8\\ -4 & -4 & -12 \end{bmatrix}\begin{bmatrix} v_1\\ v_2 \\ v_3\end{bmatrix}=\begin{bmatrix} 0\\ 0 \\0\end{bmatrix} \\$ We obtain reduced row echelon form: $\begin{bmatrix} 4 & 8 & 16\\ 4 & 0 & 8\\ -4 & -4 & -12 \end{bmatrix} \approx \begin{bmatrix} 1 & 2 & 4\\ 0 & 1 & 1\\ 0 & 0 & 0 \end{bmatrix}$ It has one unpivot column. (1) For $\lambda=-3$ let $B=A-\lambda_1I$ $B=\begin{bmatrix} 5-\lambda & 8 & 16 \\ 4 & 1-\lambda & 8\\ -4 & -4 & -11 - \lambda\end{bmatrix} =\begin{bmatrix} 8 & 8 & 16\\ 4 & 4 & 8\\ -4 & -4 & -8 \end{bmatrix}\begin{bmatrix} v_1\\ v_2 \\ v_3\end{bmatrix}=\begin{bmatrix} 0\\ 0 \\0\end{bmatrix} \\$ We obtain reduced row echelon form: $\begin{bmatrix} 8 & 8 & 16\\ 4 & 4 & 8\\ -4 & -4 & -8 \end{bmatrix} \approx \begin{bmatrix} 1 & 1 & 2\\ 0 & 0& 0\\ 0 & 0 & 0 \end{bmatrix}$ It has two unpivot columns (2) From (1) and (2), $A$, is diagonalizable. The canonical Jordan form is $J=\begin{bmatrix} 1 & 0 & 0\\ 0 & -3 & 0 \\ 0 & 0 & -3 \end{bmatrix} $
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