Решебник по алгебре 8 класс Мерзляк Задание 741

\[\boxed{\mathbf{741\ (741).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ \ x² + bx + 8 = 0\]

\[x_{1} \cdot x_{2} = 8\]

\[x_{1} + x_{2} = - b\]

\[x_{1} = 8,\ \ x_{2} = 1,\ \ b = - 9\]

\[x_{1} = - 8,\ \ x_{2} = - 1,\ \ b = 9\]

\[x_{1} = 4,\ \ x_{2} = 2,\ \ b = - 6\]

\[x_{1} = - 4,\ \ x_{2} = - 2,\ \ b = 6\]

\[\mathbf{Ответ:\ }\mathbf{при}\ b\mathbf{=} - 9;9;\ b = - 6;6.\]

\[2)\ x² + bx - 18 = 0\]

\[x_{1} \cdot x_{2} = - 18\]

\[x_{1} + x_{2} = - b\]

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

\[b = 17\]

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

\[b = - 17\]

\[x_{1} = - 9,\ \ x_{2} = 2,\ \ b = 7\]

\[x_{1} = - 2,\ \ x_{2} = 9,\ \ b = - 7\]

\[x_{1} = 6,\ \ x_{2} = - 3,\ \ b = - 3\]

\[x_{1} = - 6,\ \ x_{2} = 3,\ \ b = 3\]

\[Ответ:при\ b = 17;\ - 17;b = 7;\ \]

\[- 7;b = 3;\ - 3.\]