\4*5+1\5*6+1\6*7.1\39*40
来源：学生作业帮助网 编辑：六六作业网 时间：2024/10/04 19:32:09
\4*5+1\5*6+1\6*7.1\39*40\4*5+1\5*6+1\6*7.1\39*40\4*5+1\5*6+1\6*7.1\39*401\4*5+1\5*6+1\6*7.1\39*40=1/
\4*5+1\5*6+1\6*7.1\39*40
\4*5+1\5*6+1\6*7.1\39*40
\4*5+1\5*6+1\6*7.1\39*40
1 \4*5+1\5*6+1\6*7.1\39*40
=1/4-1/5+1/5-1/6+……+1/39-1/40
=1/4-1/40
=9/40
太简单了