问题描述: 简便计算:9.99x22.2+33.3x3.34 1/3+1/15+1/35+1/63+1/99+1/143 1个回答 分类:数学 2014-11-08 问题解答: 我来补答 9.99x22.2+33.3x3.34=0.3x33.3x22.2+33.3x3.34=33.3x(0.3x22.2+3.34)=33.3x(6.66+3.34)=33.3x10=3331/3+1/15+1/35+1/63+1/99+1/143=1/3+1/(3x5)+1/(5x7)+1/(7x9)+1/(9x11)+1/(11x13)=1/3+1/2*(1/3-1/5)+1/2*(1/5-1/7)+1/2*(1/7-1/9)+1/2*(1/9-1/11)+1/2*(1/11-1/13)=1/3+1/6-1/26=1/2-1/26=13/26-1/26=6/13 展开全文阅读