Ta có :
\(n^2+3⋮n-1\)
Mà \(n-1⋮n-1\)
\(\Leftrightarrow\left\{{}\begin{matrix}n^2+3⋮n-1\^2-n⋮n-1\end{matrix}\right.\)
\(\Leftrightarrow n-3⋮n-1\)
Mà \(n-1⋮n-1\)
\(\Leftrightarrow4⋮n-1\)
Vì \(n\in Z\Leftrightarrow n-1\in Z;n-1\inƯ\left(4\right)\)
\(n-1\) | \(1\) | \(-1\) | \(2\) | \(-2\) | \(4\) | \(-4\) |
\(n\) | \(2\) | \(0\) | \(3\) | \(-1\) | \(5\) | \(-3\) |
\(Đk\) \(n\in Z\) | TM | TM | TM | TM | TM | TM |
Vậy ===...