解:(a1^T,a2^T,a3^T,a4^T)=
1 1 1 1
1 1 0 2
1 0 0 -3
r1-r2,r2-r3
0 0 1 -1
0 1 0 5
1 0 0 -3
r1r3
1 0 0 -3
0 1 0 5
0 0 1 -1
所以 a1,a2,a3 是一个极大无关组,且 a4=-3a1+5a2-a3.
(a1^T,a2^T,a3^T,a4^T)=
1 1 1 1
1 1 0 2
1 0 0 -3
r1-r2,r2-r3
0 0 1 -1
0 1 0 5
1 0 0 -3
r1r3
1 0 0 -3
0 1 0 5
0 0 1 -1
所以 a1,a2,a3 是一个极大无关组,且 a4=-3a1+5a2-a3.
