r1-2r4,r2-r4
0 -7 8 -11
0 -7 9 -12
0 2 -5 2
1 4 0 6
按第1列展开 D=(-1)^(4+1)*
-7 8 -11
-7 9 -12
2 -5 2
r2-r1
-7 8 -11
0 1 -1
2 -5 2
c3+c2
-7 8 -3
0 1 0
2 -5 -3
= -27.