线性代数,把这个行列式化成三角行列式…求解.

=
1 -1 2 -3 1
0 0 -1 0 -2
0 2 0 4 -1
0 -2 1 -5 3
0 0 2 2 -2
= r4+r2+r3,r5+2r2
1 -1 2 -3 1
0 0 -1 0 -2
0 2 0 4 -1
0 0 0 -1 0
0 0 0 2 -6
= (-1)*
1 -1 2 -3 1
0 2 0 4 -1
0 0 -1 0 -2
0 0 0 -1 0
0 0 0 0 -6
= 12.