The Standard Form:
when a, b and c are real numbers and a must not be 0 (a ≠ 0)
We can convert it in the vertex form which is

Right now, the function takes form of intercepts, we have to convert it to the standard form as we will convert the standard form to vertex.
Distributed

At this part, we can complete the square inside as we'll get (x-h)^2 and k

The vertex is at (2, -16) [The vertex is at (-h, k) so (-(-2), -16) as we get (2, -16)]