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1/2%1/3+1/4%1/5+1/6%1/12怎样巧算

1/2-1/3+1/4-1/5+1/6-1/12=1/2-1/6+1/6-1/5=1/2-1/5=3/10直接写这3步就o了

1/3+1/4+1/5=a 1/3+1/4+1/5+1/6=b (1/2+a)*b-(1/2+b)*a =1/2(b-a) =1/2*1/6 =1/12

令:(1+1/2+1/3+1/4+1/5)=a;(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)=a(a-1+1/6)-(a+1/6)(a-1)=a-a+a/6-a+a-a/6+1/6=1/6

1/2+(1/3-1/3)+(1/4+1/4)+(1/5-1/5)-(1/6+1/6)+(1/7-1/7)+1/8=1/2+2/4+2/6+1/8=12/24+12/24+8/24+3/24=1又11/24这是我能想到最简的啊,好像以前也做过相似的呢……望采纳~

=5(1+2+3++9+10)=5*[10(10+1)/2]=5x5x11=275

a=1:2+1:5 =1*1:5+a*1:5 =1:5-a*1:4=1+a 1:2+1:3+1:4+1:5=a+1:5 1+1:3+1:4+1:2+1:5=1+a+1:5)-a(1+a+1:5) =a(1+a)+(1+a)*1:5-a(1+a)-a*1:4 则1+1:5 所以原式=(1+a)(a+1:3+1:3+1:2+1

分子=1-1/2+1/3-1/4+1/5-1/6+.+1/99-1/100=1+1/2+1/3+1/4+1/5+1/6+.+1/99+1/100-2*(1/2+1/4+1/6+.+1/100)=1+1/2+1/3+1/4+1/5+1/6+.+1/99+1/100-(1+1/2+1/3+1/4+1/5+1/6+.+1/50)=1/51+1/52+1/53+.+1/100=分母所以,原算式=1

解:原式=(1-1/2)+(1/2-1/3)+(1/3-1/4)..+(1/99-1/100)=1-1/100=99/100不懂,请追问,祝愉快

用2除以1的结果加上3除以1的结果加上4除以1的结果加上5除以1的结果加上6除以1的结果20

=(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+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11) =100+(1/2-1/11) =100+9/22 =100又9/22

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