Where is the vertex of the graph of

y = -x squared + 4x + 5

1 answer

x^2 - 4 x - 5 = -y

x^2 - 4 x = -y + 5

x^2 - 4 x + 4 = -y + 9

(x-2)^2 = -(y-9)
so
(2,9)