You can
put this solution on YOUR website!For our vertex, the equation's formula is:
(4, 5.5) is on the parabola. Put these values in our formula to find p.

Thus
And our equation becomes
Another way to think about this is that the non-vertex point you are given is only 1 unit over to the right and it goes up 3 units from the vertex, so your "a" value would logically be 3 (1 increase of x results in 3 increase in y).
I edited this because I made it more complicated than it needed to be prior to this current revision. Good day