呃 拜托,是1/2+1/6+1/12+1/20+1/30+……+1/9900好吧.回答问题一也分没有啊
裂项相消法
原式=1/(1*2)+1/(2*3)+1/(3*4)+.+1/(99*100)
=(1/1-1/2)+(1/2-1/3)+(1/3-1/4)+.+(1/99-1/100)
=1-1/2+1/2-1/3+1/3-1/4+.+1/99-1/100
=1-1/100
=99/100