ГДЗ по алгебре 8 класс Макарычев ФГОС Задание 548

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Пояснение.

Решение.

\[\textbf{а)}\ x^{2} - 8x + 9 = 0\]

\[D_{1} = 4^{2} - 9 = 16 - 9 = 7\]

\[x_{1} = 4 + \sqrt{7} \approx 6,65;\]

\[x_{2} = 4 - \sqrt{7} \approx 1,35.\]

\[Ответ:x = 6,65;\ \ x = 1,35.\]

\[\textbf{б)}\ 2y^{2} - 8y + 5 = 0\]

\[D_{1} = 4^{2} - 2 \cdot 5 = 16 - 10 = 6\]

\[y_{1} = \frac{4 + \sqrt{6}}{2} \approx 3,22;\ \ \]

\[y_{2} = \frac{4 - \sqrt{6}}{2} \approx 0,78.\ \]

\[Ответ:y = 0,78;\ \ y = 3,22.\]