UC知道1/2+1/6+1/12+1/20+........+1/9900
来源：百度知道 编辑：UC知道 时间：2024/04/28 23:08:21
速度
原式=1/1*2+1/2*3+……+1/99*100
=(1/1-1/2)+(1/2-1/3)+……+(1/99-1/100)
=1-1/100
=99/100
1/2+1/6+1/12+1/20+........+1/9900
=1/2+1/(2*3)+1/(3*4)+.......+1/(99*100)
=1/2+(1/2-1/3)+(1/3-1/4)+.......+(1/99-1/100)
=1-1/100
=99/100
原式=1/(1*2)+1/(2*3）+……+1/(99*100)
=（1-1/2)+(1/2-1/3)+……(1/99-1/100)
=1-1/100
=99/100
用的是裂项求和方法。
(1/2) (1/4+1/6)=
1/2 ，1/3 ,1/6 /1/6 ,()
1/2+1/6+1/12+1/20+1/30
1/2+1/4+1/6+1/8+.......+1/n=?
-1/2-1/6-1/12-1/20-``````````````-1/4026042
1/2+1/6+1/12+......+1/1980+1/2070=?
1/2 1/6 1/3 2 ( ) 3 1/2 数字推理
1/2*4+1/4*6+1/6*8+.......+1/2006*2008
1/2*4+1/4*6+1/6*8+1/48*50
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=