find the equation ....

Answer:
[tex]y=-\frac{1}{16}x^2[/tex]
Step-by-step explanation:
The focus of the parabola is (0,-4)
and the directrix is y=4.
The equation of this parabola is given by:
[tex]x^2=-4py[/tex]
The vertex of this parabola is at the origin.
The value of p is the distance from the vertex to the focus.
p=0--4=4
The equation of the parabola is
[tex]x^2=-4(4)y[/tex]
[tex]x^2=-16y[/tex]
Or
[tex]y=-\frac{1}{16}x^2[/tex]