Answer:
The vertex is (3,-25)
Explanation:
Quadratic Function has the form:

Lets use distributive property [a(b+c)=ab+ac] to make the equation given into the vertex form. Thus, we have:

Thus,
a = 1
b = -6
c = -16
The x coordinate of vertex is given as:

Putting the points, we have:

Putting x = 3 into the function, we get y-value of vertex:

The vertex is (3,-25)