\(3n+1⋮n+1\\ \Leftrightarrow3\left(n+1\right)-2⋮n+1\\ \Leftrightarrow2⋮n+1\\ \Leftrightarrow n+1\inƯ\left(2\right)=\left\{-2;-1;1;2\right\}\\ \Leftrightarrow n\in\left\{-3;-2;0;1\right\}\)
\(\left(3n+11\right)⋮\left(n+1\right)\)
\(\Rightarrow3\left(n+1\right)+8⋮\left(n+1\right)\)
\(\Rightarrow n+1\inƯ\left(8\right)=\left\{1;-1;2;-2;4;-4;8;-8\right\}\)
\(\Rightarrow n\in\left\{0;-2;1;-3;3;-5;7;-9\right\}\)
nhầm :vv
\(3n+11⋮n+1\\ \Leftrightarrow3\left(n+1\right)+8⋮n+1\\ \Leftrightarrow8⋮n+1\\ \Leftrightarrow n+1\inƯ\left(8\right)=\left\{-8;-4;-2;-1;1;2;4;8\right\}\\ \Leftrightarrow n\in\left\{-9;-5;-3;-2;0;1;3;7\right\}\)
Nếu bạn chưa học ước âm thì loại số âm ra
3n + 11 \(⋮\) n + 1
3n + 3 + 8 \(⋮\) n + 1
3(n+1) + 8 \(⋮\) n + 1
\(\Rightarrow\left\{{}\begin{matrix}3\left(n+1\right)⋮n+1\\8⋮n+1\end{matrix}\right.\)
8 \(⋮\) n + 1
\(\Rightarrow n+1\in\) {-8; -4; -2; -1; 1; 2; 4; 8}
| n+1 | -8 | -4 | -2 | -1 | 1 | 2 | 4 | 8 |
| n | -9 | -5 | -3 | -2 | 0 | 1 | 3 | 7 |
\(\Rightarrow n\in\left\{-9;-5;-3;-2;0;1;3;7\right\}\)