\(x\in N\Rightarrow x+1\in N\)
\(\left(x+6\right)⋮\left(x+1\right)\Rightarrow\left(x+1+5\right)⋮\left(x+1\right)\)
Mà \(\left(x+1\right)⋮\left(x+1\right)\Rightarrow5⋮\left(x+1\right)\Rightarrow x+1\inƯ\left(5\right)=\left\{1;5\right\}\Rightarrow x\in\left\{0;4\right\}\)
\(\Rightarrow x+1+5⋮x+1\\ \Rightarrow x+1\inƯ\left(5\right)=\left\{1;5\right\}\\ \Rightarrow x\in\left\{0;4\right\}\)