急求四节行列式解法级答案 3 -7 2 4 -2 5 1 -3 2 -5 -1 2 4 -6 3 8

2025-01-03 02:38:57
推荐回答(2个)
回答1:

回答2:

3 -7 2 4
-2 5 1 -3
2 -5 -1 2
4 -6 3 8

r2+r3
3 -7 2 4
0 0 0 -1
2 -5 -1 2
4 -6 3 8

按第2行展开
D = -1 * (-1)^(2+4) *
3 -7 2
2 -5 -1
4 -6 3

r1+2r2,r3+3r2
7 -17 0
2 -5 -1
10 -21 0

按第2行展开
D = -1*(-1)*(-1)^(2+3)*
7 -17
10 -21

= -23