9等于8与1的和,7等于8与1的差,原算式可以看作123乘以8与1的和之积加上82乘以8的积只和加上47乘以8与1的差之积的和,计算过程如下:
123x9+82x8+47x7
=123x(8+1)+82x8+47x(8-1)
=123x8+123+82x8+47x8-47
=184+123+656+336-47
=184+656+123+336-47
=840+123+336-47
=963+336-47
=1299-47
=1252
9等于8与1的和,7等于8与1的差,原算式可以看作123乘以8与1的和之积加上82乘以8的积只和加上47乘以8与1的差之积的和,计算过程如下:
123x9+82x8+47x7
=123x(8+1)+82x8+47x(8-1)
=123x8+123+82x8+47x8-47
=184+123+656+336-47
=184+656+123+336-47
=840+123+336-47
=963+336-47
=1299-47
=1252