1/8+1/24+1/48+1/80+.+1/360 =
问题描述：
1/8+1/24+1/48+1/80+.+1/360 =
答
请检查一下你的题目
1/2×4+1/4×6+1/6×8+……+1/18×20
=(1/2-1/4+1/4-1/6+1/6-1/8+……+1/18-1/20)/2
=9/40