(1+1/2+1/3+1/4)×(1/2+1+1/3+1/4+1/5)×(1/2+1/3+1/4) =简便方法

(1+1/2+1/3+1/4)×(1/2+1+1/3+1/4+1/5)×(1/2+1/3+1/4) =简便方法
(1+1/2+1/3+1/4)×(1/2+1+1/3+1/4+1/5)×(1/2+1/3+1/4) =简便方法

(1+1/2+1/3+1/4)×(1/2+1+1/3+1/4+1/5)×(1/2+1/3+1/4) =简便方法
你的题目写错了,检查一下,再向我追问