\[y = \frac{x + 2}{\sqrt{3x - 12x^{2}\ }}\]
\[3x - 12x^{2} > 0\]
\[3x(1 - 4x) = 0\]
\[x = 0,\ \ \ x = 0,25\]
\[Ответ:D(y) = (0;\ 0,25)\text{.\ }\]