Answer:
y = -(x - 2)^2.
Step-by-step explanation:
Vertex form is a(x - b)^2 + c where a is a constant and (b, c) is the vertex.
Here b = 2 and c = 0
So we have:
y = a( x - 2)^2 + 0
When x = 4 y = -4 so:
-4 = a( 4 - 2)^2
a = -4/2^2 = -1
So the required equation is
y = -(x - 2)^2.
