解:
|A-λE|
=
-1-λ
3
3
3
-1-λ
3
3
3
-1-λ
=
5-λ
3
3
5-λ
-1-λ
3
5-λ
3
-1-λ
=
5-λ
3
3
0
-4-λ
0
0
0
-4-λ
=
(5-λ)(-4-λ)^2.
A的特征值为5,-4,-4
(A-5E)X=0
的基础解系为:
a1=(1,1,1)^T
(A+4E)X=0
的基础解系为:
a2=(1,-1,0)^T,a3=(1,0,-1)^T
令P=(a1,a2,a3),
则P可逆,
且
P^-1AP=diag(5,-4,-4).