问题描述: (1/8+1/24+1/48+1/80+1/120+1/168+1/224+1/288)×128=_____. 1个回答 分类:数学 2014-11-17 问题解答: 我来补答 (1/8+1/24+1/48+1/80+1/120+1/168+1/224+1/288)×128=128×(1/8)[1+1/3+1/6+1/10+1/15+1/21+1/28+1/36] =128×(1/8)[1+2(1/(2×3)+1/(3×4)+1/(4×5)+1/(5×6)+1/(6×7)+1/(7×8)+1/(8×9)] =128×(1/8)[1+2(1/2-1/3+1/3-1/4+...+1/8-1/9] =128×(1/8)[1+2(1/2-1/9)] =128×(1/8)[1+1-2/9] =128×(1/8)(16/9) =256/9 第一步提1/8第二步提2第三步1/2-1/3=1/61/3-1/4=1/121/4-1/5=1/201/5-1/6=1/301/6-1/7=1/421/7-1/8=1/561/8-1/9=1/72 展开全文阅读