向量的加法符合下列运算规律 (1)交换律:a+b=b+l (2)结合律:a+b+C=(+b)+c=+(b+c) (3)d+(-d)=0. 2减法a-b=a+(-b) b b ra+b C=l+(-b) b =a-b向量的加法符合下列运算规律: (1)交换律: a b b a. + = + (2)结合律: a b c a b c + + = ( + ) + a (b c). = + + (3) ( ) 0. a + −a = [2] 减法 a b a ( b) − = + − a b b − b c − a b c a b = − = + (− ) a b + a b a − b