[tex]\it 2x+1|6x+23\ \ \ \ \ (1)\\ \\ Dar, \ \ 2x+1|2x+1 \Rightarrow 2x+1|(2x+1)\cdot3 \Rightarrow 2x+1|6x+3 \ \ \ \ \ (2)\\ \\ (1),\ (2) \Rightarrow 2x+1|6x+23-6x-3 \Rightarrow 2x+1|20 \Rightarrow 2x+1\in\{1, 2, 4, 5, 10, 20\}|_{-1} \Rightarrow \\ \\ \Rightarrow 2x\in\{0,\ 1, \ 3,\ 4, \ 9, 19\}[/tex]
Dar, 2x = număr par, deci 2x ∈ {0, 4} |:2 ⇒ x ∈ {0, 2}