利用行列式性质计算1111 11-1-1 1-11-1 1-1-11

1 1 1 1
1 1 -1 -1
1 -1 1 -1
1 -1 -1 1
=
1 1 1 1
0 0 -2 -2
0 -2 0 -2
0 -2 -2 0
=
1 1 1 1
0 0 -2 -2
0 -2 0