1/（3*7）+1/(7*11)+1/(11*15)+.+1/(55*59)等于多少?
问题描述：
1/（3*7）+1/(7*11)+1/(11*15)+.+1/(55*59)等于多少?
如题.
答
1/（3*7）+1/(7*11)+1/(11*15)+.+1/(55*59) =1/4(1/3-1/7+1/7-1/11+1/11-1/15+.+1/55-1/59) =1/4(1/3-1/59) =1/4(56/177) =14/177