Question 1176629
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Hi

Using the vertex form of a parabola, {{{y=a(x-h)^2 +k}}} 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

{{{y = -.25(x+2)^2 + 4}}}, 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