Ta có: \(\dfrac{2}{1}< \dfrac{1}{n}< \dfrac{4}{7}\)
\(\Rightarrow\dfrac{4}{2}< \dfrac{4}{4n}< \dfrac{4}{7}\)
\(\Rightarrow2< 4n< 7\)
\(\Rightarrow0,5< n< 1,75\)
Mà \(n\in N\)
\(\Rightarrow n=1\)
Vậy n = 1
\(\dfrac{2}{1}< \dfrac{1}{n}< \dfrac{4}{7}\)
\(\Rightarrow\dfrac{4}{2}< \dfrac{4}{4n}< \dfrac{4}{7}\)
\(\Rightarrow2< 4n< 7\)
\(\Rightarrow\dfrac{2}{4}< \dfrac{n}{4}< \dfrac{7}{4}\)
\(\Rightarrow0,5< n< 1,75\)
\(n\in N\Rightarrow n=1\)