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1又1/2+2又1/6+3又1/12+4又1/20+5又1/30+6又1/42+7...

1又1/2+2又1/6+3又1/12+4又1/20+5又1/30+6又1/42+7又1/56 =(1+2+3+4+5+6+7)+(1/2+1/6+1/12+1/20+1/30+1/42+1/56) =4×7+(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) =28+(1-1/8) =28+7/8 =28又7/8

我觉得直接计算后两者相加,再向前加就可以,很简便 望采纳

1/2+1/6+1/12+1/20+1/30+1/42 =1/(1x2)+1/(2x3)+1/(3x4)+1/(4x5)+1/(5x6)+1/(6x7) =(1 -1/2) +(1/2-1/3)+...+(1/6-1/7) =1 -1/7 =6/7 异分母分数相加: 1、异分母分数相加,先通分,再按同分母分数相加法去计算,最后要化成最简分数。 例1:3/4+...

1又1/2+2又1/6+3又1/12+4又1/20+5又1/30+6又1/42 =1+1/2+2+1/6+3+1/12+4+1/20+5+1/30+6+1/42 =(1+2+3+4+5+6)+(1/2+1/6+1/12+1/20+1/30+1/42) =21+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7) =21+(1-1/7) =21+6/7 =21又6/7

如图

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

二又3/20-(5/6-1/12) =2+3/20+1/12-5/6 =2-(50/60-9/60-5/60) =2-36/60 =2-3/5 =1又5分之2

1/2和1/3分数单位不同,无法直接加减。 必须先统一分数单位——通分。2.和3的最小公倍数是6,用6作1/2、1/3的公分母。 1/2=3/6;1/3=2/6;这样就可以进行加减了。 1/2+1/3 =3/6+2/6 =5/6(3个1/6+2个1/6=5个1/6也就是5/6) 1/20+1/30 =3/60+2/60 =...

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