Question

8.對(duì)于向量a、b、c和實(shí)數(shù)，下列命題中真命題是

A.若a·b＝0，則a=0或b=0                            B.若a=0,則＝0或a=0

C.若a²=b2,則a=b或a=-b                                D.若a·b=a·c，則b=c

Answer 1

B

解析：排除法.A中a·b=0a⊥b;

C中a²=b²a²－b²=0(a+b)·(a－b)=0;

D中a·b=a·ca·(b－c)=0.