a) Ta có:
\(2n+3⋮n\)
\(\Rightarrow3⋮n\)
\(\Rightarrow n\in U\left(3\right)=\left\{-1;1;-3;3\right\}\)
\(\Rightarrow n=\left\{-1;1;-3;3\right\}\)
Vậy \(n=\left\{-1;1;-3;3\right\}\)
b) Ta có:
\(2n+3⋮n+1\)
\(\Rightarrow\left(2n+2\right)+1⋮n+1\)
\(\Rightarrow2\left(n+1\right)+1⋮n+1\)
\(\Rightarrow1⋮n+1\)
\(\Rightarrow n+1\in U\left(1\right)=\left\{-1;1\right\}\)
\(\Rightarrow n\in\left\{-2;0\right\}\)
Vậy \(n\in\left\{-2;0\right\}\)