2.向量加法的运算规律 b bta (1)交换律 atb=bta a+b+c (2)结合律 atb +C (a+b)+C=a+(b+c)2. 向量加法的运算规律. (1) 交换律: a b b a     + = + a b   + a  b  c  b c   + a b c    + + (2) 结合律: (a b) c a (b c)       + + = + + a  b  a  b  a b   + b a   +