系数矩阵 A =
2 3 -1 -7
3 1 2 -7
4 1 -3 6
1 -2 5 -5
r3-r2-r4,r2-r1-r4,r1-2r4
0 7 -11 3
0 0 -2 5
0 2 -10 18
1 -2 5 -5
r4+r3,r3*(1/2),r1-7r3
0 0 24 -60
0 0 -2 5
0 1 -5 9
1 0 -5 13
r1*(1/24),r2+2r1,r3+5r1,r4+5r1
0 0 1 -5/2
0 0 0 0
0 1 0 -7/2
1 0 0 1/2
交换行
1 0 0 1/2
0 1 0 -7/2
0 0 1 -5/2
0 0 0 0
方程组的通解为:c(-1,7,5,2)^T.