[tex]\it x\in\mathbb{N},\ x+1|x+6.\ x=?\\ \\ Rezolvare : \\ \\ x+1|x+6\ \ \ \ (1)\\ \\ Dar,\ x+1|x+1\ \ \ \ (2)\\ \\ (1),\ (2)\Rightarrow x+1|x+6-x-1 \Rightarrow x+1|5 \Rightarrow x+1\in D_5\Rightarrow\\ \\ \Rightarrow x+1\in\{1,\ 5\}|_{-1} \Rightarrow x\in\{0,\ 4\}[/tex]
