Finding the Vertex of a Quadratic Function

Consider the quadratic equation given by the function $f(x) = 3x^2 - 12x + 9$. The function describes a parabola that opens upward. Find the x-coordinate of the vertex of this parabola. The x-coordinate can be found using the formula $x = -\frac{b}{2a}$, where $a$ and $b$ are the coefficients of $x^2$ and $x$, respectively.

Once you have determined the x-coordinate, compute the corresponding value of $f(x)$ at that x-coordinate to get the y-coordinate of the vertex. The final answer should be entered as a grid-in response, representing the x-coordinate of the vertex.