(a1,a2,a3,a4)=
1 -2 -1 2
-2 4 2 -6
2 -1 0 3
3 3 3 4
r2+2r1,r3-2r1,r4-3r1
1 -2 -1 2
0 0 0 -2
0 3 2 -1
0 9 6 -2
r2*(-1/2),r1-2r2,r3+r2,r4+2r2
1 -2 -1 0
0 0 0 1
0 3 2 0
0 9 6 0
r4-3r3,r3*(1/3),r1+2r3
1 0 1/3 0
0 0 0 1
0 1 2/3 0
0 0 0 0
向量组的秩为3,向量组线性相关
a1,a2,a4 是M的一个极大无关组,且 a3=(1/3)a1+(2/3)a2.