what are the coordinates of the vertex of f(x)=-x^2+6x-9

Question

(0,-9)
(3,-9)
(3,0)
(6,0)

How do I figure this out?

Answer 1

the vertex is on the axis of symmetry

x = -b / (2 a) = -6 / (2 * -1) = 3

plug 3 into the function to find the y-coordinate