(49-1/8)×1/8+(46-1/8)×1/8+(43-1/8)×1/8+……+(1-1/8)=

问题描述:

(49-1/8)×1/8+(46-1/8)×1/8+(43-1/8)×1/8+……+(1-1/8)=

=(49+46+43+...+4)x1/8-16/8x1/8+7/8=(4+49)x8/8-16/64+7/8=53-1/4+7/8=53又5/8