\[x^{2} - 5x - 36 < 0\]
\[x^{2} - 5x - 36 = 0\]
\[x_{1} + x_{2} = 5\ \ \ \ \ \ \ \ \ x_{1} = 9\]
\[x_{1} \cdot x_{2} = - 36\ \ \ \ \ x_{2} = - 4\]
\[Ответ:x \in ( - 4;9)\text{.\ }\]