1\30+1\42+1\56+1\72+1\90+1\110,简便计算

悠悠悠云淡 1年前 已收到3个回答 举报

ldp850110 花朵

共回答了24个问题采纳率:91.7% 举报

1/30=1/5乘以1/6=(6-5)/6成5=1/5-1/6
所以130+142+156+172+190+1110
=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年前

3

请别握住我的手 幼苗

共回答了4个问题 举报

=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年前

0

wxf2006 花朵

共回答了4434个问题 举报

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

1年前

0
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