设向量组{a1,a2,a3,a4}线性无关,b1=a1+k1a4,b2=a2+k2a4,b3=a3+k3a4,b4=a4,证明向量组{b1,b2,b3

2025-06-28 09:35:07
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回答1:

解答:证明:由b1=a1+k1a4,b2=a2+k2a4,b3=a3+k3a4,b4=a4
(b1b2b3b4)=(a1a2a3a4)

1 0 0 0
0 1 0 0
0 0 1 0
k1 k2 k3 1

1 0 0 0
0 1 0 0
0 0 1 0
k1 k2 k3 1
=1≠0

1 0 0 0
0 1 0 0
0 0 1 0
k1 k2 k3 1
可逆,
从而R(b1,b2,b3,b4)=R(a1,a2,a3,a4),
由{a1,a2,a3,a4}线性无关,得
R(b1,b2,b3,b4)=R(a1,a2,a3,a4)=4等于{b1,b2,b3,b4}中向量的个数,
故{b1,b2,b3,b4}线性无关.