- #1
Dustinsfl
- 2,281
- 5
Make matrix defective if possible and identify the values of alpha.
[tex]\begin{bmatrix}
3\alpha & 1 & 0\\
0 & \alpha & 0\\
0 & 0 & \alpha
\end{bmatrix}[/tex]
Skipping the boring stuff we obtain [itex](\alpha-\lambda)^2(3\alpha-\lambda)=0[/itex] as the characteristic polynomial.
[tex]\lambda_1=\lambda_2=\alpha[/tex] and [tex]\lambda_3=3\alpha[/tex]
For lambda being alpha
[tex]\begin{bmatrix}
2\alpha & 1 & 0\\
0 & 0 & 0\\
0 & 0 & 0
\end{bmatrix}\Rightarrow \begin{bmatrix}
1 & \frac{-1}{2\alpha} & 0\\
0 & 0 & 0\\
0 & 0 & 0
\end{bmatrix}\Rightarrow x_2\begin{bmatrix}
\frac{-1}{2\alpha}\\
1\\
0
\end{bmatrix}+x_3\begin{bmatrix}
0\\
0\\
1
\end{bmatrix}[/tex]
For this lambda value, the matrix can't be defective? Not sure though.
For lambda being 3alpha
[tex]\begin{bmatrix}
0 & 1 & 0\\
0 & -2\alpha & 0\\
0 & 0 & -2\alpha
\end{bmatrix}\Rightarrow \begin{bmatrix}
0 & 1 & 0\\
0 & 0 & 1\\
0 & 0 & 0
\end{bmatrix}\Rightarrow x_1\begin{bmatrix}
1\\
0\\
0
\end{bmatrix}[/tex]
And for this one, alpha can be any value and the matrix will be defective.
[tex]\begin{bmatrix}
3\alpha & 1 & 0\\
0 & \alpha & 0\\
0 & 0 & \alpha
\end{bmatrix}[/tex]
Skipping the boring stuff we obtain [itex](\alpha-\lambda)^2(3\alpha-\lambda)=0[/itex] as the characteristic polynomial.
[tex]\lambda_1=\lambda_2=\alpha[/tex] and [tex]\lambda_3=3\alpha[/tex]
For lambda being alpha
[tex]\begin{bmatrix}
2\alpha & 1 & 0\\
0 & 0 & 0\\
0 & 0 & 0
\end{bmatrix}\Rightarrow \begin{bmatrix}
1 & \frac{-1}{2\alpha} & 0\\
0 & 0 & 0\\
0 & 0 & 0
\end{bmatrix}\Rightarrow x_2\begin{bmatrix}
\frac{-1}{2\alpha}\\
1\\
0
\end{bmatrix}+x_3\begin{bmatrix}
0\\
0\\
1
\end{bmatrix}[/tex]
For this lambda value, the matrix can't be defective? Not sure though.
For lambda being 3alpha
[tex]\begin{bmatrix}
0 & 1 & 0\\
0 & -2\alpha & 0\\
0 & 0 & -2\alpha
\end{bmatrix}\Rightarrow \begin{bmatrix}
0 & 1 & 0\\
0 & 0 & 1\\
0 & 0 & 0
\end{bmatrix}\Rightarrow x_1\begin{bmatrix}
1\\
0\\
0
\end{bmatrix}[/tex]
And for this one, alpha can be any value and the matrix will be defective.
Last edited: