2n + 7 \(⋮\)n - 3
\(\Leftrightarrow\)2(n - 3) + 6 + 7 \(⋮\)n - 3
\(\Leftrightarrow\)13\(⋮\)n - 3
\(\Leftrightarrow\)n - 3 \(\in\)Ư(13) = {\(\pm\)1 ;\(\pm\)13}
\(\Leftrightarrow\)n \(\in\){4 ; 2 ; 16 ; - 10}
Ta có: \(2n+7⋮n-3\)
=> \(2\left(n-3\right)+13⋮n-3\)
=> \(13⋮n-3\)
Vì \(n\in Z\Rightarrow n-3\inƯ\left(13\right)=\left\{\pm1;\pm13\right\}\)
Ta có bảng sau:
n-3 | 1 | -1 | 13 | -13 |
n | 4 | 2 | 16 | -10 |
Vậy \(n\in\left\{4;2;16;-10\right\}\)