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|
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