[tex]\it 1.\ \ \dfrac{n^2+n}{2n+6}=\dfrac{n(n+1)}{2(n+3)}\\ \\ \\ 2|n(n+1\ \ \c{s}i\ \ 2|2(n+3)) \Rightarrow frac\c{\it t}ia\ dat\breve a\ este\ reductibil\breve a[/tex]
[tex]\it 2.\ a)\ \dfrac{n}{3n+1}\\ \\ \\ Fie\ d\in\mathbb{N}^*\ astfel\ ca\ \begin{cases}\it d|n \Rightarrow d|3n\\ \\ \c{s}i\\ \\ \it d|{3n+1}\end{cases} \Rightarrow d|3n+1-3n \Rightarrow d|1 \Rightarrow d=1 \Rightarrow\\ \\ \\ \Rightarrow \dfrac{n}{3n+1}\ este\ frac\c{\it t}ie\ ireductibil\breve a[/tex]
