1又1\/2+3又1\/6+5又1\/12+7又1\/20+9又1\/42+11又1\/56+13又1\/72+
=(1+3+..+15)+(1\/2+1\/2-1\/3+1\/3-1\/4+..+1\/9-1\/10)=64+1-1\/10=65-1\/10=64又9\/10
1又1\/2+3又1\/6+5又1\/12+7又1\/20+9又1\/42+11又1\/56+13又1\/72+15又1...
1又1\/2+3又1\/6+5又1\/12+7又1\/20+9又1\/42+11又1\/56+13又1\/72+15又1\/90 =(1+3+5+7+9+11+13+15)+(1\/2+1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90-1\/30)= 64+1\/(1*2 )+1\/(2*3 )+1\/(3*4) +1\/(4*5)+1\/(5*6)+1\/(6*7)+1\/(7*8)+1\/(8*...
1+3又1\/6+5又1\/12+7又1\/20+9又1\/30+11又1\/42+13又1\/56+15又1\/72+17...
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 ...
1+3又1\/6+5又1\/12+7又1\/20+9又1\/30+11又1\/42+13又1\/56+15又1\/72+17...
思路:1\/6=1\/2-1\/3 、1\/12=1\/3-1\/4 、………1+3又1\/6+5又1\/12+7又1\/20+9又1\/30+11又1\/42+13又1\/56+15又1\/72+17又1\/90+19又1\/110 =(1+3+5+7+9+11+13+15+17+19)+(1\/6+1\/12+1\/20+1\/30+1\/42+1\/56+1\/72+1\/90+1\/110)=20×5+(1\/2-1\/3+1\/...
1+3又1\/6+5又1\/12+7又1\/20+9又1\/30+11又1\/42等于多少?
1+3又1\/6+5又1\/12+7又1\/20+9又1\/30+11又1\/42 =(1+3+5+7+9+11)+(1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+1\/5-1\/6+1\/6-1\/7)=6×6+(1\/2-1\/7)=36又5\/14
简便计算 一加三又六分之一加五又十二分之一加七又二十分之一加九又...
先把整数部分拿出来算:1+3+5+7+9+11=36 再算分数部分 1\/6+1\/12+1\/20+1\/30+1\/42 =1\/(2*3)+1\/(3*4)+……+1\/(6*7)=(1\/2-1\/3)+(1\/3-1\/4)+……+(1\/6-1\/7) =1\/2-1\/7=5\/14 最后答案就是36+5\/14 ...
1+2又6分之1+3又12分之1+4又20分之1+5又30分之1+6又42分之1+7又56分...
原式=(1+2+3+...+9)+(1\/6 +1\/12+1\/20+...+1\/90)=45+[1\/(2×3)+1\/(3×4)+1\/(4×5)+...+1\/(9×10)]=45+1\/2 -1\/3 +1\/3 -1\/4+ 1\/4 -1\/5+...+1\/9 -1\/10 =45+ 1\/2 -1\/10 =45又5分之2 ...
1+3又六分之一加五又十二分之一加七又二十分之一加九分之三十分之一九...
原式=1+3+5+7+1\/6+1\/12+1\/21+3\/9+19\/10 =16+2\/12+1\/12+1\/21+1\/3+1+9\/10 =17+5\/20+18\/20+1\/21+7\/21 =18+3\/20+8\/21 =18+63\/420+160\/420 =18又223\/420
1+3又6分之1+5又12分之1+7又20分之1+9又30分之1+11又42分之1+13又56...
=1+3+5+7+9+11+13+15+17+1\/6+1\/12+1\/20+...+1\/90 =(1+17)+(3+15)+(5+13)+(7+11)+9+1\/(2*3)+1\/(3*4)+1\/(4*5)+...+1\/(9*10)=18*4+9+1\/2-1\/3+1\/3-1\/4+1\/4-1\/5+...-1\/9+1\/9-1\/10 =81+1\/2-1\/10 =81又5分之2 ...
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