\[y = - 3x^{2} + bx + c;\ \ \ A(1; - 8).\]
\[x = - \frac{b}{2a}\]
\[1 = - \frac{b}{- 3 \cdot 2}\]
\[1 = \frac{b}{6}\]
\[b = 6.\]
\[- 8 = - 3 \cdot 1 + 6 \cdot 1 + c\]
\[c = - 8 - 3\]
\[c = - 11.\]
\[Ответ:b = 6;\ \ c = - 11.\]