题目求指导本题解题过程,谢谢您!5.设a1,a2,β1,β2是3维列向量, =((a)_(1),(a)_(2),(beta )_(1)) , =((a)_(1),2(a)_(2),(beta )_(2)), 且 |A|=1,-|||-|B|=2, 则 |A+B|= __ _。求指导本题解题过程,谢谢您!题目解答答案