\[x^{2} + bx + c = 0\]
\[- 9\ \ и\ 12:\]
\[- b = - 9 + 12\ \ \]
\[- b = 3 \Longrightarrow b = - 3.\]
\[c = - 9 \cdot 12 \Longrightarrow c = - 108.\]
\[Ответ:b = - 3;c = - 108.\]