Hi
Using the vertex form of a parabola,
where(h,k) is the vertex
Vertex (-2,4)
y = a(x+2)^2 + 4
P(-6,0)
0 = 16a+ 4
-4/16 = a = -.25
, the vertex form of a parabola
As to Standard form (If necessary):
y =-.25(x^2 + 4x + 4) + 1 =-.25x^2 - x - 1 + 4 = -.25x^2 - x + 3