(a1,a2,a3,a4,a5)=
1 1 1 2 2
0 2 -1 1 5
2 0 3 3 -1
1 1 -1 0 4
r3-2r1,r4-r1
1 1 1 2 2
0 2 -1 1 5
0 -2 1 -1 -5
0 0 -2 -2 2
r3+r2,r4*(-1/2),r1-r4,r2+r4
1 1 0 1 3
0 2 0 2 4
0 0 0 0 0
0 0 1 1 -1
r2*(1/2),r2-r2
1 0 0 0 1
0 1 0 1 2
0 0 0 0 0
0 0 1 1 -1
所以向量组的秩为3, a1,a2,a3 是一个极大无关组
且 a4=a2+a3,a5=a1+2a2-a3.