问题标题:
A=[a1,a2,a3]B=[3a1-2a2,3a2-2a3,2a3-a1-2a2]|B|=28求|A|
问题描述:
A=[a1,a2,a3]B=[3a1-2a2,3a2-2a3,2a3-a1-2a2]|B|=28求|A|
陆玲回答:
B=[3a1-2a2,3a2-2a3,2a1-a2]=[-a1,6a1-2a3,2a1-a2]=[-a1,-2a3,-a2]
=-2[a1,a3,a2]=2[a1,a2,a3]=2A
A=14
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