Answer:
Step-by-step explanation:
I'm not sure how you are finding this in class, but the easiest way by far is to use the expressions for h and k:
and
(Just a fun fact: Those expressions come from the quadratic formula that help us to factor a quadratic equation.)
Filling in for h:
simplifies to
Filling in for k:
which simplifies a bit to
which simplifies a bit more to
The vertex, then, is (4, -25).
You would also find this if you completed the square. But again, I'm not sure how you're solving for the vertex in class.