1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=
来源:百度知道 编辑:UC知道 时间:2024/05/13 08:47:32
帮帮忙.
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/(6*7)+1/(7*8)+1/(8*9)+1/(9*10)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10
=1-1/10
=9/10
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90 = 0.9
(1/1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+(1/7-1/8)+(1/8-1/9)+(1/9-1/10)=1-1/10=9/10
(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=