问题描述: 1/35+1/63+1/99+1/143 用简便方法计算 1个回答 分类:数学 2014-11-14 问题解答: 我来补答 1/35+1/63+1/99+1/143=1/(5*7)+1/(7*9)+1/(9*11)+1/(11*13)=(1/2)*[(1/5)-(1/7)]+(1/2)*[(1/7)-(1/9)]+(1/2)*[(1/9)-(1/11)]+(1/2)*[(1/11)-(1/13)]=(1/2)*[(1/5)-(1/7)+(1/7)-(1/9)+(1/9)-(1/11)+(1/11)-(1/13)]=(1/2)*[(1/5)-(1/13)]=(1/2)*(8/65)=4/65 展开全文阅读