3+r4,r1+2r2,r4-3r2
0 7 -3 3
-1 4 -7 0
0 9 9 -1
0 -11 21 4
r1+3r3,r4+4r3
0 34 24 0
-1 4 -7 0
0 9 9 -1
0 25 57 0
(若学过行列式展开定理,按第1列展开,再按最后一列展开就行了)
r1r2,c2c3,r2r3
-1 0 -7 4
0 -1 9 9
0 0 24 34
0 0 57 25
所以 D=(-1)^3 (24*25 - 34*57) = 1338
3+r4,r1+2r2,r4-3r2
0 7 -3 3
-1 4 -7 0
0 9 9 -1
0 -11 21 4
r1+3r3,r4+4r3
0 34 24 0
-1 4 -7 0
0 9 9 -1
0 25 57 0
(若学过行列式展开定理,按第1列展开,再按最后一列展开就行了)
r1r2,c2c3,r2r3
-1 0 -7 4
0 -1 9 9
0 0 24 34
0 0 57 25
所以 D=(-1)^3 (24*25 - 34*57) = 1338