=1+½-3+1/6+3+1/12-5+1/20+5+1/30-7+1/42+7+1/56-9+1/72+9+1/90
=1+1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90
=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
=2-1/10
=19/10
1½-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又41\/42+7又1\/56-8又71\/7...
1½-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又41\/42+7又1\/56-8又71\/72+9又1\/90 =1+½-3+1\/6+3+1\/12-5+1\/20+5+1\/30-7+1\/42+7+1\/56-9+1\/72+9+1\/90 =1+1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90 =1+1\/2+1\/2-1\/3+1\/3-1\/4+...
1又1\/2-2又5\/6+3又1\/12-4 又19\/20+5又1\/30-6又41\/42+7又1\/56-8又71\/...
先把整数位提出来只剩分数1\/2-1+1\/6+1\/12-1+1\/20+1\/30-1+1\/42+1\/56-1+1\/72+1\/90=1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90-4=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\/10-4=9\/10-4 分数这么...
1.求1又1\/2-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又41\/42+7又1\/56-8又...
1、1又1\/2-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又41\/42+7又1\/56-8又71\/72+9又1\/90 =（1-3+3-5+5-7+7-9+9）+（1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90 =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又1\/2-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又41\/42+7又1\/56-8又71\/7...
=1+1\/2-3+1\/6+3+1\/12-5+1\/20+5+1\/30-7+1\/42+7+1\/56—9+1\/72+9+1\/10 =（1-3+3-5+5-7+7-9+9）+（1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90）=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...
数学1又2分之1-2又6分之5-3又12分之1-4又20分之9+5又30分之1-6又42分...
裂项法：1又1\/2-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又41\/42+7又1\/56-8又71\/72+9又1\/90 =2-1\/2-3+1\/6+3+1\/12-5-1\/20+5+1\/30-7+1\/42+7+1\/56-9+1\/72+9+1\/90 =（2-3+3-5+5-7+7-9-9）+（-1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90...
1又1\/2-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又41\/42+7又1\/56-8
=1-3+3-5+5-7+7-9+9 +(1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90)=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+1-1\/10 =1又9\/10 ...
求教解题过程! 1又1\/2-2又5\/6+3又1\/12-4又19\/20+5又1\/30-6又14\/42
比如7又1\/90=7+1\/9×10=7+1\/9-1\/10
...+9又1\/30+11又1\/42+13又1\/56+15又1\/72+17又1\/90=???
×项数\/2来算，(1+17)×9\/2=81。对后半部分，1\/6=1\/(2×3)=1\/2 - 1\/3，以此类推后面的分数都可以依此展开，就是(1\/2 - 1\/3)+(1\/3 - 1\/4)+(1\/4 - 1\/5)+...+(1\/9 - 1\/10),中间项彼此抵消，等于1\/2 - 1\/10=2\/5。故原式=81又2\/5,或写成407\/5 ...
做出这到题1 1\/2-2 5\/6+3 1\/12-4 19\/20+5 1\/30-6 41\/42+7 1\/56-8 7...
1.9 我用VBS算得，保证对！dim b b=1+1\/2-2-5\/6+3+1\/12-4-19\/20+5+1\/30-6-41\/42+7+1\/56-8-71\/72+9+1\/90 msgbox(b)除非我电脑坏了。
1又1\/12+3又1\/6+5又1\/12+7又1\/20+9又1\/30等于多少?
1 + 3 + 5 + 7 + 9 = 25 接下来，将每个分数部分相加，得到：1\/12 + 3\/12 + 5\/12 + 7\/12 + 9\/12 = 25\/12 最后，将整数部分和分数部分相加，得到最终结果：25 + 25\/12 = 25 1\/12 因此，1又1\/12 + 3又1\/6 + 5又1\/12 + 7又1\/20 + 9又1\/30 = 25 1\/12。
