a) n+4 ⋮ n
Mà n⋮n
=>4⋮n
=> n \(\inƯ\left(4\right)=\left\{1;2;4\right\}\)
b) 3n+7⋮n
Mà 3n⋮n
=>7⋮n
=> n \(\inƯ\left(7\right)=\left\{1;7\right\}\)
ta có:\(n+4⋮n\)
\(\Rightarrow n⋮n\Rightarrow4⋮n\)
\(\Rightarrow n\inƯ\left(4\right)=\left\{1,2,4\right\}\)