1-r2,r3-3r2,r4-r2
0 0 3 -4
1 -1 -1 2
0 4 8 -4
0 -2 -11 4
r3*(1/4),r2+r3,r4+2r3
0 0 3 -4
1 0 1 1
0 1 2 -1
0 0 -7 2
r1+2r4
0 0 11 0
1 0 1 1
0 1 2 -1
0 0 -7 2
r1*(1/11),r2-r1,r3-2r1,r4+7r1
0 0 1 0
1 0 0 1
0 1 0 -1
0 0 0 2
r4*(1/2),r2-r4,r3+r4
0 0 1 0
1 0 0 0
0 1 0 0
0 0 0 1
交换行
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1