3+r21,r4+r2
5 0 4 7
1 -1 2 1
5 0 4 1
2 0 3 2
按第2列展开,D=-1*
5 4 7
5 4 1
2 3 2
r1-r2
0 0 6
5 4 1
2 3 2
D = -1*6*(5*3-2*4) = -42.
3+r21,r4+r2
5 0 4 7
1 -1 2 1
5 0 4 1
2 0 3 2
按第2列展开,D=-1*
5 4 7
5 4 1
2 3 2
r1-r2
0 0 6
5 4 1
2 3 2
D = -1*6*(5*3-2*4) = -42.