\[y = \frac{\sqrt{x^{2} + 2x - 80}}{3x - 36}\]
\[x^{2} + 2x - 80 \geq 0\]
\[D = 1 + 80 = 81\]
\[x_{1} = 1 + 9 = 10;\ \ \ \]
\[x_{2} = 1 - 9 = - 8\]
\[(x + 8)(x - 10) \geq 0.\]
\[3x - 36 > 0\]
\[3x > 36\]
\[x > 12.\]
\[Ответ:x \in ( - \infty; - 10\rbrack \cup \lbrack 8;12) \cup (12; + \infty).\]