ГДЗ по алгебре 8 класс Макарычев Задание 553

\[75a^{2} - 25a - 2 = 0\]

\[D = 625 + 600 = 1225\]

\[a_{1,2} = \frac{25 \pm \sqrt{1225}}{2 \cdot 75} = \frac{25 \pm 35}{150}\]

\[a_{1} = \frac{60}{150} = \frac{6}{15} = \frac{2}{5} = 0,4;\]

\[a_{2} = - \frac{10}{150} = - \frac{1}{15}.\]

\[Ответ:при\ a = 0,4;\ \ a = - \frac{1}{15}.\]

\[40a + 120 = 16a^{2} + 144\]

\[2a^{2} - 5a + 3 = 0\]

\[D = 25 - 24 = 1\]

\[a_{1,2} = \frac{5 \pm \sqrt{1}}{2 \cdot 2} = \frac{5 \pm 1}{4}\]

\[a_{1} = \frac{4}{4} = 1\]

\[a_{2} = \frac{6}{4} = \frac{3}{2} = 1,5\ \]

\[Ответ:при\ a = 1;\ \ a = 1,5.\]