系数矩阵 =
2 -3 1 -1 3
3 1 1 1 0
4 -1 -1 -1 7
-2 -1 1 1 -5
r4+r3,r3*(1/7)
2 -3 1 -1 3
3 1 1 1 0
1 0 0 0 1
-2 -1 1 1 -5
r1-2r3,r2-3r3,r4+2r3
0 -3 1 -1 1
0 1 1 1 -3
1 0 0 0 1
0 -1 1 1 -3
r1-3r2,r4+r2
0 0 4 2 -8
0 1 1 1 -3
1 0 0 0 1
0 0 2 2 -6
r4*(1/2),r1-4r4,r2-r4,
0 0 0 -2 4
0 1 0 0 0
1 0 0 0 1
0 0 1 1 -3
r1*(-1/2),
0 0 0 1 -2
0 1 0 0 0
1 0 0 0 1
0 0 1 0 -1
交换行
1 0 0 0 1
0 1 0 0 0
0 0 1 0 -1
0 0 0 1 -2
得方程组的解:x1=1,x2=0,x3=-1,x4=-2