1又1／6＋2又1／12＋3又1／20＋4又1／30＋5又1／42＋6又1／56＋7又1／72 奥数题，求过程与结果，急急急急

Answer 1

1+2+3+。。。+7+1/2-1/3+1/3-1/4+...1/8-1/9=28+7/18

Answer 2

=(1+2+3+4+5+6+7)+(1/2×3+1/3×4+1/4×5+1／5×6+1/6×7+1/7×8+1/8×9)
=28+(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)
=28+(1/2-1/9)
=28又7/18

Answer 3

7/6+25/12+61/20+121/30+211/42+337/56+505/72=511/18=28又7/18

Answer 4

1+1/6+2+1/12+3+1/20+4+1/30+5+1/42+6+1/56+7+1/72=1+2+3+4+5+6+7+(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)=28+7/18

Answer 5

大概豆腐干