1-r3,r2-2r3,r4+3r3
r2*(1/4),r1-5r2,r4-r2
r4-r1,r1*(1/4),r2+r1,r3-r1
r1r3
1 0 0 14/9
0 1 0 -5/9
0 0 1 4/9
0 0 0 0
字数受限, 只给了步骤