2.性质 设A,B,C,O都是m×n矩阵 (1)A+B=B+A (2)(A+B)+C=A+(B+C) (3)A+O=0+A=A2. 性质 设 A，B，C，O 都是 m×n 矩阵 (1) A + B = B + A (2) ( A + B ) + C = A + ( B + C ) (3) A + O = O + A = A