\[y = x^{2} - 6x + 3\]
\[a > 0 - ветви\ вверх.\]
\[x_{0} = - \frac{b}{2a} = \frac{6}{2} = 3;\]
\[y_{0} = 9 - 18 + 3 = - 6.\]
\[Вершина\ O(3; - 6).\]