ГДЗ по алгебре 8 класс Макарычев ФГОС Задание 717

\[\boxed{\text{717.}\text{\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]

\[\textbf{а)}\ 9x^{2} - 100 = 0\]

\[9x^{2} = 100\]

\[x^{2} = \frac{100}{9}\]

\[x = \pm \frac{10}{3} = \pm 3\frac{1}{3}.\]

\[Ответ:x = \pm 3\frac{1}{3}.\]

\[\textbf{б)}\ 2 = 7c^{2}\]

\[c^{2} = 3,5\]

\[c = \pm \sqrt{3,5}.\]

\[Ответ:c = \pm \sqrt{3,5}.\]

\[\textbf{в)}\ 9m^{2} - 4 = 0\]

\[9m^{2} = 4\]

\[m^{2} = \frac{4}{9}\]

\[m = \pm \frac{2}{3}.\]

\[Ответ:m = \pm \frac{2}{3}.\]

\[\textbf{г)} - 0,8y^{2} + 3y = 0\]

\[- 0,8y\left( y - \frac{30}{8} \right) = 0\]

\[y = 0;\ \ \ y = \frac{30}{8} = \frac{15}{4} = 3,75.\]

\[Ответ:y = 0;\ \ y = 3,75.\]