1/6+1/12+1/20+…+1/90=?
来源:百度知道 编辑:UC知道 时间:2024/06/08 00:43:08
速度,急用!!!
1/6+1/12+1/20+…+1/90
=1/(2*3)+1/(3*4)+1/(4*5)+....+1/(9*10)
=1/2-1/3+1/3-1/4+1/4-1/5+.....+1/9-1/10
=1/2-1/10
=2/5
解:1/6+1/12+1/20+…+1/90
=1/2×3+1/3×4+1/4×5+。。。+1/9×10
=1/2-1/3+1/3-1/4+1/4-1/5+。。。+1/9-1/10
=1/2-1/10
=2/5
1/6可分成1/2减1/3,1/12可分成1/3减1/4,依次分,最后变成1/2减1/10,得2/5。手打,认为好给分
原式=(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+…+(1/9-1/10)
=1/2-1/10
=2/5
原式=(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+…+(1/9-1/10)
=1/2-1/10
=2/5
(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+......+(1/9-1/10)=1/2-1/3+1/3-1/4+1/4-1/5+....+1/9-1/10=1/2-1/10=2/5
1/2+1/6+1/12+1/20+1/30
1/6+1/8+1/10+1/12+..........+1/202=?
-1/2-1/6-1/12-1/20-``````````````-1/4026042
1/2+1/6+1/12+......+1/1980+1/2070=?
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?
计算1/2 +1/6+1/12+1/20+1/30+1/42=
求解1/2-1/6-1/12-1/20-1/30-1/42
1/2+1/6+1/12+1/20+1/30......1/9900
1/3+1/6+1/12+1/24+1/48+…+1/1588