1 0 1 1 0 0
-2 0 1 0 1 0
1 1 -1 0 0 1
等价
1 0 1 1 0 0
0 0 3 2 1 0
0 1 -2 -1 0 1
等价
1 0 1 1 0 0
0 1 -2 -1 0 1
0 0 3 2 1 0
等价
1 0 1 1 0 0
0 1 -2 -1 0 1
0 0 1 2/3 1/3 0
等价
1 0 0 1/3 -1/3 0
0 1 0 1/3 2/3 1
0 0 1 2/3 1/3 0
所以
逆矩阵为：
1/3 -1/3 0
1/3 2/3 1
2/3 1/3 0