1\30+1\42+1\56+1\72+1\90+1\110,简便计算

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1\30+1\42+1\56+1\72+1\90+1\110,简便计算
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1\30+1\42+1\56+1\72+1\90+1\110,简便计算
1\30+1\42+1\56+1\72+1\90+1\110,简便计算

1\30+1\42+1\56+1\72+1\90+1\110,简便计算
1/30=1/5乘以1/6=(6-5)/6成5=1/5-1/6
所以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
=1/5-1/11
=6/55

=1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11
=1/5-1/11
=6/55

1/30+1/42+1/56+1/72+1/90+1/110
=1/(5*6)+1/(6*7)+1/(7*8)+1/(8*9)+1/(9*10)+1/(10*11)
=1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11
=1/5-1/11
=11/55-5/11
=6/11