题目
1.求矩阵A=}0&0&10&1&01&0&0的特征值与特征向量.2.判断A=}3&2&-20&-1&04&2&-3是否可对角化,若可对角化,则求出对角矩阵与相似变换矩阵.
1.求矩阵$A=\begin{pmatrix}0&0&1\\0&1&0\\1&0&0\end{pmatrix}$的特征值与特征向量.
2.判断$A=\begin{pmatrix}3&2&-2\\0&-1&0\\4&2&-3\end{pmatrix}$是否可对角化,若可对角化,则求出对角矩阵与相似变换矩阵.
题目解答
答案
1. **特征值与特征向量**
特征方程:
\[
\det(\lambda I - A) = (\lambda - 1)^2 (\lambda + 1) = 0 \implies \lambda_1 = -1, \lambda_2 = \lambda_3 = 1
\]
**特征向量:**
- 对于 $\lambda_1 = -1$:$\mathbf{v}_1 = k \begin{pmatrix} -1 \\ 0 \\ 1 \end{pmatrix}$
- 对于 $\lambda_2 = \lambda_3 = 1$:$\mathbf{v}_2 = k_1 \begin{pmatrix} 1 \\ 0 \\ 1 \end{pmatrix} + k_2 \begin{pmatrix} 0 \\ 1 \\ 0 \end{pmatrix}$
2. **可对角化判断**
特征值:$\lambda_1 = 1, \lambda_2 = \lambda_3 = -1$
**特征向量:**
- $\lambda_1 = 1$:$\mathbf{v}_1 = k \begin{pmatrix} 1 \\ 0 \\ 1 \end{pmatrix}$
- $\lambda_2 = \lambda_3 = -1$:$\mathbf{v}_2 = s \begin{pmatrix} -\frac{1}{2} \\ 1 \\ 0 \end{pmatrix} + t \begin{pmatrix} \frac{1}{2} \\ 0 \\ 1 \end{pmatrix}$
**结论:**可对角化,对角矩阵 $D = \begin{pmatrix} 1 & 0 & 0 \\ 0 & -1 & 0 \\ 0 & 0 & -1 \end{pmatrix}$,相似变换矩阵 $P$ 可取为
\[
\boxed{
\begin{pmatrix}
1 & -1 & 1 \\
0 & 2 & 0 \\
1 & 0 & 2
\end{pmatrix}
\]