\(A=\dfrac{n}{n+1}+\dfrac{2}{n+1}=\dfrac{n+2}{n+1}=\dfrac{n+1}{n+1}+\dfrac{2}{n+1}=1+\dfrac{2}{n+1}\)
Để A là số tự nhiên => \(n+1\inƯ\left(2\right)=\left\{-2,-1,1,2\right\}\)
n+1 | -2 | -1 | 1 | 2 |
n | -3 | -2 | 0 | 1 |
A | 0 | -1 (loại) | 3 | 2 |
Vậy \(n\in\left\{0;2;3\right\}\)