\[\boxed{\text{226\ (226).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[(n - 3)x^{2} + (n + 1)x +\]
\[+ 9 - 2n = 0\]
\[\left\{ \begin{matrix} n - 3 \geq 1\ \ \\ n + 1 \geq 1\ \ \\ 9 - 2n \geq 1 \\ \end{matrix} \right.\ \Longrightarrow \left\{ \begin{matrix} n \geq 4\ \ \\ n \geq 0\ \ \\ 2n \leq 8 \\ \end{matrix} \right.\ \Longrightarrow\]
\[\Longrightarrow \left\{ \begin{matrix} n \geq 4 \\ n \geq 0 \\ n \leq 4 \\ \end{matrix} \right.\ \Longrightarrow n = 4.\]
\[n = 4 \Longrightarrow (n - 3)x^{2} +\]
\[+ (n + 1)x + 9 - 2n =\]
\[= x^{2} + 5x + 1.\]
\[Ответ:x^{2} + 5x + 1.\]