\4*5+1\5*6+1\6*7.1\39*40

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/17 18:58:38

\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