Решебник по алгебре 8 класс Мерзляк Задание 790

\[\boxed{\mathbf{790\ (790).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\frac{30}{x + 3} + \frac{1}{2} - \frac{30}{x} = 0;\ \ \ \ x \neq 0;\ \]

\[x \neq - 3\]

\[x^{2} + 3x - 180 = 0\]

\[D = 9 + 720 = 729\]

\[x = \frac{- 3 - 27}{2} = - 15\]

\[x = \frac{- 3 + 27}{2} = 12\]

\[Ответ:\ x = - 15;x = 12.\]

\[2)\ \frac{20}{x + 18} + 9 - \frac{20}{x} = 0\ \ \ \ \ \ \ \]

\[x \neq 0;\ \ \ x \neq - 18\]

\[9x² + 162x - 360 = 0\ \ \ \ \ |\ :9\]

\[x^{2} - 18x - 40 = 0\]

\[x_{1} + x_{2} = 18,\ \ x_{1}x_{2} = - 40,\ \ \]

\[x_{1} = - 20,\ \ x_{2} = 2\]

\[Ответ:\ x = - 20;x = 2.\]