a: =>6 chia hết cho n+2
\(\Leftrightarrow n+2\in\left\{1;-1;2;-2;3;-3;6;-6\right\}\)
hay \(n\in\left\{0;1;4\right\}\)
b: =>n-1+6 chia hết cho n-1
\(\Leftrightarrow n-1\in\left\{1;-1;2;-2;3;-3;6;-6\right\}\)
hay \(n\in\left\{2;0;3;4;7\right\}\)
c: =>2n+1+6 chia hết cho 2n+1
\(\Leftrightarrow2n+1\in\left\{1;3\right\}\)
hay \(n\in\left\{0;1\right\}\)
d: =>3n-3+7 chia hết cho n-1
\(\Leftrightarrow n-1\in\left\{1;-1;7\right\}\)
hay \(n\in\left\{2;0;8\right\}\)