解: D =
r3-3r1
1 1 2 2
0 1 1 3
0 0 -1 -2
0 -4 -6 -7
r4+4r2
1 1 2 2
0 1 1 3
0 0 -1 -2
0 0 -2 5
r4-2r3
1 1 2 2
0 1 1 3
0 0 -1 -2
0 0 0 9
= -9.
解: D =
r3-3r1
1 1 2 2
0 1 1 3
0 0 -1 -2
0 -4 -6 -7
r4+4r2
1 1 2 2
0 1 1 3
0 0 -1 -2
0 0 -2 5
r4-2r3
1 1 2 2
0 1 1 3
0 0 -1 -2
0 0 0 9
= -9.