a/ \(n+5⋮n-1\)

Mà \(n-1⋮n-1\)

\(\Leftrightarrow6⋮n-1\)

\(\Leftrightarrow n-1\inƯ\left(6\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}n-1=1\-1=2\-1=3\-1=6\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}n=2\=3\=4\=7\end{matrix}\right.\)

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b/ \(2n-4⋮n+2\)

Mà \(n+2⋮n+2\)

\(\Leftrightarrow\left\{{}\begin{matrix}2n-4⋮n+2\\2n+4⋮n+2\end{matrix}\right.\)

\(\Leftrightarrow8⋮n+2\)

\(\Leftrightarrow n+2\inƯ\left(8\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}n+2=1\+2=2\+2=4\+2=8\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}n=-1\=0\=2\=6\end{matrix}\right.\)

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