\[\boxed{\mathbf{711\ (711).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ x² + bx + c = 0\]
\[x_{1} = - 8\]
\[x_{2} = 6\]
\[x_{1} + x_{2} = - b = - 8 + 6 = - 2,\]
\[b = 2\]
\[x_{1} \cdot x_{2} = c = - 8 \cdot 6 = - 48,\ \ \]
\[c = - 48\]
\[Ответ:b = 2;\ \ c = - 48.\]
\[2)\ x² + bx + c = 0\]
\[x_{1} = 4\]
\[x_{2} = 5\]
\[x_{1} + x_{2} = - b = 4 + 5 = 9,\ \ \]
\[b = - 9\]
\(x_{1} \cdot x_{2} = c = 4 \cdot 5 = 20,\ \ c = 20\ \)
\[Ответ:b = - 9;\ \ c = 20.\]