数与矩阵相乘 数入与矩阵A的乘积记作A或A,规定为 九a,几 12 A=42aa211a2 2n a., 2数与矩阵相乘 数与矩阵A的乘积记作A或A，规定为 11 12 1 21 22 2 1 2 n n m m mn a a a a a a A A a a a     = =                     