\[\boxed{\mathbf{310}.}\]
\[1)\ x^{3} + 3x^{2} - 25x - 75 = 0;\ \]
\[\ x_{1} = - 3:\]
\[x^{2} - 25 = 0\]
\[x^{2} = 25\]
\[x = \pm 5.\]
\[Ответ:x = \pm 5;\ \ x = - 3.\]
\[2)\ 2x^{3} + x^{2} - 4x - 2 = 0;\ \ \]
\[x_{1} = - \frac{1}{2}:\]
\[2x^{2} - 4 = 0\]
\[2x^{2} = 4\]
\[x^{2} = 2\]
\[x = \pm \sqrt{2}.\]
\[Ответ:x = \pm \sqrt{2};\ \ x = - 0,5.\]