用展开定理吧
c2+3c1,c4-2c1
1 0 0 0
3 11 -1 1
-2 -1 4 5
-4 1 -5 2
= 按第1行展开
11 -1 1
-1 4 5
1 -5 2
r1+11r2,r2+r3
0 43 56
0 -1 7
1 -5 2
= 按第1列展开
43 56
-1 7
= 43*7 + 56
= 357.