Để n + 1 chia hết cho 5
\(\Rightarrow n+1\inƯ\left(5\right)\)
\(\Rightarrow n+1\in\left\{-1;1;-5;5\right\}\)
\(\Rightarrow n+1=-1\Rightarrow n=-2\)
\(\Rightarrow n+1=1\Rightarrow n=0\)
\(\Rightarrow n+1=-5\Rightarrow n=-6\)
\(\Rightarrow n+1=5\Rightarrow n=4\)