2)
[tex] \it \dfrac{9}{2x+1} \in\mathbb{Z} \Rightarrow 2x+1 \in D_9 \Rightarrow 2x+1 \in \{\pm1,\ \pm3,\ \pm9\} \Rightarrow
\\ \\ \\
\Rightarrow 2x+1 \in \{-9,\ -3,\ -1,\ 1,\ 3,\ 9 \}|_{-1} \Rightarrow 2x\in \{-10,\ -4,\ -2,\ 0,\ 2,\ 8 \} |_{:2}
\\ \\ \\
\Rightarrow x \in \{-5,\ -2,\ -1,\ 0,\ 1,\ 4 \} [/tex]
