1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
问题描述:
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)
答
1/2+(2/3+1/3)+(3/4+2/4+1/4)+……+(39/40+38/40+……2/40+1/40)