题目

求向量组 的秩和极大无关组.
求向量组 a1(1 0 2 1 ),a2(1 2 0 1 ) ,a3(2 1 3 0 ) ,a4(2 5 -1 4) ,a5(1 -1 3 -1)的秩和极大无关组.

提问时间：2021-03-31

答案

(a1,a2,a3,a4,a5)=
1 1 2 2 1
0 2 1 5 -1
2 0 3 -1 3
1 1 0 4 -1
r3-2r1,r4-r1
1 1 2 2 1
0 2 1 5 -1
0 -2 -1 -5 1
0 0 -2 2 -2
r3+r2,r4*(-1/2)
1 1 2 2 1
0 2 1 5 -1
0 0 0 0 0
0 0 1 -1 1
到此可知秩=3.
极大无关组:a1,a2,a3
r1-2r4,r2-r4
1 1 0 4 -1
0 2 0 6 -2
0 0 0 0 0
0 0 1 -1 1
r2*(1/2)
1 1 0 4 -1
0 1 0 3 -1
0 0 0 0 0
0 0 1 -1 1
r1-r2,r3r4
1 0 0 1 0
0 1 0 3 -1
0 0 1 -1 1
0 0 0 0 0
其余向量由极大无关组表示为:
a4 = a1+3a2-a3
a5 = -a2 +a3