При каких x имеет смысл выражение корень из (x^2+x-72)?

\[\sqrt{x^{2} + x - 72}\]

\[x^{2} + x - 72 \geq 0\]

\[x^{2} + x - 72 = 0\]

\[x_{1} + x_{2} = - 1\]

\[x_{1} \cdot x_{2} = - 72\]

\[x_{1} = - 9;\ \ \ x_{2} = 8\]

\[Ответ:x \in ( - \infty;\ - 9\rbrack \cup \lbrack 8; + \infty).\]

\[\ 5x² - 17x - 12 > 0\]

\[5x^{2} - 17x - 12 = 0\]

\[D = b^{2} - 4ac = 289 - 4 \cdot 5 \cdot ( - 12) =\]

\[= 289 + 240 = 529\]

\[x_{1} = \frac{17 + 23}{10} = \frac{40}{10} = 4\]

\[x_{2} = \frac{17 - 23}{10} = - \frac{6}{10} = - 0,6\]

\[Ответ:\ x \in ( - \infty; - 0,6) \cup (4; + \infty).\]