题目

3/2-17/6+37/12-99/20+151/30-293/42+393/56-647/72+811/90等于多少,有谁知道,知者肯定给分.

提问时间：2020-07-31

答案

原式=(1+2)/2-(18-1)/6+(36+1)/12-(100-1)/20+(150+1)/30-(292-1)/42+(294-1)/42+(392+1)/56-(648-1)/72+(810+1)/90
=1+1/2-3+1/6+3+1/12-5+1/20+5+1/30-7+1/42+7+1/56-9+1/72+9+1/90
=1+1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=1+1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10
=1+1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10
=19/10