用初等变换求逆矩阵：设A =3 -2 0 -1 0 2 2 1 1 -2 -3 -2 0 1 2 1 快···

(A,E) =
3 -2 0 -1 1 0 0 0
0 2 2 1 0 1 0 0
1 -2 -3 -2 0 0 1 0
0 1 2 1 0 0 0 1
r1-3r3 (第1行减3倍的第3行)
0 4 9 5 1 0 -3 0
0 2 2 1 0 1 0 0
1 -2 -3 -2 0 0 1 0
0 1 2 1 0 0 0 1
r1-4r4,r2-2r4,r3+2r4
0 0 1 1 1 0 -3 -4
0 0 -2 -1 0 1 0 -2
1 0 1 0 0 0 1 2
0 1 2 1 0 0 0 1
r2+2r1,r3-r1,r4-2r1
0 0 1 1 1 0 -3 -4
0 0 0 1 2 1 -6 -10
1 0 0 -1 -1 0 4 6
0 1 0 -1 -2 0 6 9
r1-r2,r3+r2,r4+r2
0 0 1 0 -1 -1 3 6
0 0 0 1 2 1 -6 -10
1 0 0 0 1 1 -2 -4
0 1 0 0 0 1 0 -1
交换行得
1 0 0 0 1 1 -2 -4
0 1 0 0 0 1 0 -1
0 0 1 0 -1 -1 3 6
0 0 0 1 2 1 -6 -10

1 0 0 0 1 1 -2 -4
0 1 0 0 0 1 0 -1
0 0 1 0 -1 -1 3 6
0 0 0 1 2 1 -6 -10