chg2008
花朵
共回答了29个问题采纳率：82.8% 举报
分析：5/6=1/2+1/3 7/12=1/3+1/4 9/20=1/4+1/5 11/30=1/5+1/6 13/42=1/6+1/7 15/56=1/7+1/8
1/2+5/6-7/12+9/20-11/30+13/42-15/56
=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)
=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
=1/2+1/2-1/8
=1-1/8
=7/8
1年前
17
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