3右乘列向量（列组合）： C=AB=A[b1,b2,·,bp]=Ahb1,Ab2,·,Abp] 4左乘行向量（行组合）： aTB a2TB C=AB= B= am B ·矩阵乘法运算律 (AB)C =A(BC),Associative A(B+C)=AB+AC,Distributive over matrix addition AB BA,Not commutative 10/813 右乘列向量（列组合）: C = AB = A [b1, b2, · · · , bp] = [Ab1, Ab2, · · · , Abp] 4 左乘行向量（行组合）: C = AB =      a1 T a2 T . . . am T      B =      a1 TB a2 TB . . . am TB      ▶ 矩阵乘法运算律: (AB)C = A(BC), Associative A(B + C) = AB + AC, Distributive over matrix addition AB ̸= BA, Not commutative 10 / 81