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3 1 -1 2-5 1 3 -42 0 1 -11 -5 3 -1

题目详情
3 1 -1 2
-5 1 3 -4
2 0 1 -1
1 -5 3 -1
▼优质解答
答案和解析
r2-r1,r4+5r1
3 1 -1 2
-8 0 4 -6
2 0 1 -1
16 0 -2 9
c1c2
D = (-1)*
1 3 -1 2
0 -8 4 -6
0 2 1 -1
0 16 -2 9
r2+4r3,r4-8r3
1 3 -1 2
0 0 8 -10
0 2 1 -1
0 0 -10 17
r2r3
D = (-1)*(-1)*
1 3 -1 2
0 2 1 -1
0 0 8 -10
0 0 -10 17
= 1*2*(8*17-10*10)
= 72.