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1/6+1/12+1/20+…+1/72+1/90+1/110=

1/6+1/12+1/20+…+1/72+1/90+1/110 =1/2-1/3+1/3-1/4+1/4-1/5+.......+1/9-1/10+1/10-1/11 =1/2-1/11 =11/22+2/22 =9/22 =22分之9 朋友,请采纳正确答案,你们只提问,不采纳正确答案,回答都没有劲!!! 朋友,请【采纳答案】,您的采纳是我答...

2分之1+6分之1+12分之1+20分之1+30分之1+42分之1+56分之1+72分之1+90分之1+110分之1 =(1-2分之1)+(2分之1-3分之1)+(3分之1-4分之1)+(4分之1-5分之1)+(5分之1-6分之1)+(6分之1-7分之1)+(7分之1-8分之1)+(8分之1-9分之1)+(9分之1...

原式拆分,连续抵消,结果是1/3-1/11=8/33

1-1/6+1/42+1/56+1/72+1/90+1/110 =1-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11 =1-1/11 =10/11

1/(n*(n+1)=1/n-1/(n+1)。所以以“1/110”为例。1/110=1/10-1/11。所以原式=1+1-1/2+1/2+1/3-1/4+……1/13-1/14。中间几项约去。只剩“1+1-1/14”。所以,答案为27/14

1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 =1/1*2+1/2*3+……+1/10*11 =(1/1-1/2)+(1/2-1/3)+……+(1/10-1/11) =1/1-1/11 =10/11

你写的42/1是表示四十二分之一? 如果是,我们习惯写成1/42 下面,按我的理解来帮你做。 1/42+1/56+1/72+1/90+1/110+1/132 =1/(6×7)+1/(7×8)+1/(8×9)+1/(9×10)+1/(10×11)+1/(11×12) =1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11+1/11-1/12 =1...

解: 原式 =(1+3+5+……+19)+(1/6+1/12+1/20+……+1/110) =(1+19)x10÷2+(1/2x3+1/3x4+1/4x5+……+1/10x11) =100+(1/2-1/3+1/3-1/4+1/4-1/5+……+1/10-1/11) =100+(1/2-1/11) (中间正负抵消了) =100+(11/22-2/22) =100又9/22

1/42+1/56+1/72+1/90+1/110+1/132 =1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11+1/11-1/12 =1/6-1/12 =1/12

对于相邻两个数的乘积要敏感,就像2、6、12、20、30、42、56、72、90、110等, 这种数作为分母时候,就要化成两个分数的和或差,此题为差, 1/30+1/42+1/56+1/72+1/90+1/110 =1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11 =1/5-1/...

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