8/3*5+8/5*7+8/7*9+8/9*11……+8/23*25简便计算回答简单点,有分哦
问题描述:
8/3*5+8/5*7+8/7*9+8/9*11……+8/23*25简便计算回答简单点,有分哦
答
原式=8(1/(3*5)+1/(5*7)+...+1/(23*25))=8[1/2(1/3-1/5)+1/2(1/5-1/7)+...+1/2(1/23-1/25)]
=4(1/3-1/25)=88/75
答
=4*(1/3-1/5-1/5-1/7+……+1/23-1/25)
=4*(1/3-1/25)
=88/75