Question

E4. Să se rezolve inecuațiile:
a) modul de (3n+1/n) - 3 modul inchis, mai mare decat 1/5, n apartine multimii nr naturale stelat

Answer 1

$\it \Big|\dfrac{3n+1}{n}\ -\ ^{n)}3\Big|>\dfrac{1}{5} \Rightarrow\Big |\dfrac{3n+1-3n}{n}\Big|>\dfrac{1}{5} \Rightarrow \dfrac{1}{n}>\dfrac{1}{5} \Rightarrow n<5 \Rightarrow \\ \\ \\ \Rightarrow n\in\{1,\ 2,\ 3,\ 4\}$