\[y = ax^{2} + bx + c;\ \ \ E\ (4;3);\ \ \ \ \ \]
\[\text{F\ }(2;1).\]
\[x_{0} = \frac{- b}{2a} = 4\ \ \ \ \ \ \ \ \]
\[b = - 8a.\]
\[ax^{2} - 8ax + c = 3\]
\[16a - 32a + c = 3\]
\[- 16a + c = 3\]
\[Ответ:a = - \frac{1}{2};\ \ b = 4;\ \ c = - 5.\]