设3阶方阵a=(a1,a2,a3),其中ai(i-1,2,3)为A的列向量,且|a|=2,则|b|=|a1+3a2,a2,a3|=( ) A.-2 B.0 C.2 D.6
问题描述:
设3阶方阵a=(a1,a2,a3),其中ai(i-1,2,3)为A的列向量,且|a|=2,则|b|=|a1+3a2,a2,a3|=( ) A.-2 B.0 C.2 D.6
答
|b| = |a1+3a2,a2,a3|
= |a1,a2,a3|
= |A| = 2
选 (C).