问题描述： 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 用简便 急 1个回答 分类：数学 2014-10-17 问题解答： 我来补答 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 =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+1/10*11=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+1/10-1/11=1-1/11=10/11 展开全文阅读
