(a1,a2,a3,a4,a5)=
1 -2 1 0 1
1 -1 0 1 2
2 -3 2 2 1
-1 4 -3 2 1
r2-r1,r3-2r1,r4+r1
1 -2 1 0 1
0 1 -1 1 1
0 1 0 2 -1
0 2 -2 2 2
r1+2r2,r3-r2,r4-2r2
1 0 -1 2 3
0 1 -1 1 1
0 0 1 1 -2
0 0 0 0 0
r1+r3,r2+r3
1 0 0 3 1
0 1 0 2 -1
0 0 1 1 -2
0 0 0 0 0
所以 r(a1,a2,a3,a4,a5)=3, a1,a2,a3 是一个极大无关组
a4 = 3a1+2a2+a3
a5 = a1-a2-2a3