1 1 2-5 6加7 12-9 20 11 30-14 42.
来源:学生作业帮助网 编辑:作业帮 时间:2024/05/12 18:32:52
1/6+1/12+1/20+1/30+1/42+1/56+1/72=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=1/2-1/9=7/
1/2-1/3+1/3-1/4……+1/9-1/10=1/2-1/10=2/5
1/6=(1/2)*(1/3),1/12=(1/3)*(1/4),1/20=(1/4)*(1/5),1/30=(1/5)*(1/6),1/42=(1/6)*(1/7),1/56=(1/7)*(1/8)
仔细看就会发现1/6=1/2-1/3,1/12=1/3-1/4...它们是有规律的原式=1+12+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
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=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
1/6+1/12+1/72+1/30+1/20+1/42+1/56=(12+6+1)/72+(3+2)/60+(4+3)/168=19/72+1/12+1/24=(19+6+3)/72=28/72=7
1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+(1/7-1/8)+(
=1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8=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=1-1
很容易(12+23+45)+(56+4)+(67+3)-4-3=203(因为是67分之1即67)(2.3+6.7)+(3.4+5.6)+2+4.5=24.5
不晓得 你是不是少了个1/30若果是就再加1/30 如过不是就是这个答案
=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/
1/6+1/12+1/20+1/42+1/56+1/72+1/90=(2+1)/12+(21+10+7.5)/420+(10+8)/720=1/4+11/120+1/40=(30+11+3)/120=
1/2+1/2-1/3+1/3-1/4+1/4-1/5+.-.-1/10=9/10求最佳!
八十八再答:��л
1/2+1/6+1/12+1/20+1/30+1/42+1/56=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)+1/*(6*7)+1/(7*8)=1-1/2+1/2-
624
原式=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/
这个不难掌握方法就行
二分之一加6分之一加12分之一加20分之一加30分之一加42分之一加五十六分之一=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=1-1/8