(a1,a2,a3,a4) =
-1 2 2 1
2 -1 2 7
2 2 -1 -2
r2+2r1,r3+2r1
-1 2 2 1
0 3 6 9
0 6 3 0
r1*(-1),r3-2r2,r2*(1/3)
1 -2 -2 -1
0 1 2 3
0 0 -9 -18
r3*(-1/9),r1+2r3,r2-2r3
1 -2 0 3
0 1 0 -1
0 0 1 2
r1+2r2
1 0 0 1
0 1 0 -1
0 0 1 2
向量组的秩为3,a1,a2,a3 是一个极大无关组.
a4 = a1-a2+2a3.