27 + 5n \(⋮\) n + 4
5n + 27 \(⋮\) n + 4
5n + 20 + 7 \(⋮\) n + 4
4(n + 4) + 7 \(⋮\) n + 4
\(\Rightarrow\left\{{}\begin{matrix}4\left(n+4\right)⋮n+4\\7⋮n+4\end{matrix}\right.\)
7 \(⋮\) n + 4
\(\Rightarrow\) n + 4 \(\in\) Ư (7) = {-7; -1; 1; 7}
n+4 | -7 | -1 | 1 | 7 |
n | -11 | -5 | -3 | 3 |
n \(\in\) {-11; -5; -3; 3}