Answer:
y = - x²
Step-by-step explanation:
Since the vertex is at the origin and the focus at (0, - 4) then the parabola opens vertically down with equation
x² = 4py ( p is the distance from the vertex to the focus )
Here p = - 4 ( focus is below the vertex ), thus
x² = 4(- 4)y = - 16y ( divide both sides by - 16 )
y = - x²