\[\frac{\sqrt{7x - x^{2}}}{4 - x^{2}}\]
\[\left\{ \begin{matrix}
7x - x^{2} \geq 0 \\
4 - x^{2}
eq 0\ \ \\
\end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\left\{ \begin{matrix}
x(x - 7) \leq 0 \\
x
eq \pm 2\ \ \ \ \ \ \ \ \ \ \ \\
\end{matrix} \right.\ \]
\[x(x - 7) \leq 0\]
\[0 \leq x \leq 7.\]
\[\left\{ \begin{matrix}
0 \leq x \leq 7 \\
x
eq \pm 2\ \ \ \ \ \ \\
\end{matrix} \right.\ \]
\[D(y) = \lbrack 0;2) \cup (2;7\rbrack.\]