问题描述: 1/20+1/30+1/42+……+1/9900等于多少? 1个回答 分类:数学 2014-11-20 问题解答: 我来补答 1/20+1/30+1/42+……+1/9900=1/(4×5)+1/(5×6)+1/(6×7)+……+1/(99×100)=(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+……(1/99-1/100)=1/4-1/5+1/5-1/6+1/6-1/7+……+1/99-1/100=1/4-1/100=25/100-1/100=24/100=6/25 展开全文阅读