\(12⋮n-1\)
\(\Rightarrow n-1\inƯ\left(12\right)\)
\(Ư\left(12\right)=\left\{\pm1;\pm2;\pm3;\pm4;\pm6;\pm12\right\}\)
\(\Rightarrow\left\{{}\begin{matrix}n-1=1\Rightarrow n=2\-1=-1\Rightarrow n=0\-1=2\Rightarrow n=3\-1=-2\Rightarrow n=-1\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}n-1=3\Rightarrow n=4\-1=-3\Rightarrow n=-2\-1=4\Rightarrow n=5\-1=-4\Rightarrow n=-3\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}n-1=6\Rightarrow n=7\-1=-6\Rightarrow n=-5\-1=12\Rightarrow n=13\-1=-12\Rightarrow n=-11\end{matrix}\right.\)
