Thank you for the opportunity to help you with your question!
I'd suggest starting with a plot, just a sketch, really. If you do it, you see that the graph of f(x) is a parabola that opens up and that when x = 7, f(x) = 5. The vertex, then is the point (7,5). You can see that geometrically. f(x) is symmetric about the (vertical) line x = 7. You can see it algebraically by noting that, for example,