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1/6-1/42-1/56-1/72-1/90-1/110等于多少

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

1-1/6+1/42+1/56+1/72+1/90+1/110=1-1/6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11=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==========如果答案对你有所帮助,记得好评哦~~

1-1/6-1/42-1/56-1/72-1/90=1-1/6-1/6+1/7-1/7+1/8-1/8+1/9-1/9+1/10=1-1/6-1/6+1/10=2/3+1/10=23/30

1/42+1/56+1/72+1/90+1/110=1/(6*7)+1/(7*8)+1/(8*9)+1/(9*10)+1/(10*11)=1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11=1/6-1/11=5/66(请注意:1/42=1/(6*7)=1/6-1/7,后面方法相同.这是解题的关键)满意请采纳答案

142+156+172+190+1110=1/6*7+1/7*8+1/8*9+1/9*10+1/10*11=1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11=1/6-1/11=5/66

因为:42=2*3*7;56=2*2*2*7;72=2*2*2*9;90=2*3*3*5;110=2*5*11;132=2*2*3*11 所以其公倍数为21*28*45*55*66=69049800 其分子为21/69049800+28/69049800+45/69049800+55/69049800+66/69049800=4573800+3430350+2134440+1746360+1455300=13340250 答案:13340250/69049800

1\42+1\56+1\72+1\90+1\110 =(1/6-1/7)+(1/7-1/8)+(1/8-1/9)+(1/9-1/10)+(1/10-1/11) =1/6-1/11 去括号 =11/66-6/66=5/66

5/66

1-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90-1/110=1-(1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110)=1-(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)=1-(1/2-1/11)=1-1/2+1/11=1/2+1/11=13/22

1-1/6+1/42+1/56+1/72=5/6*7+1/42+1/56+1/72=6/7*8+1/56+1/72=7/8*9+1/72=8/9.

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