Given that the directrix is at y = 4 and the focus is at (0, -4), then the vertex is at (h, k) = (0, 0). p is the distance between the vertex and the focus and between the vertex and the directrix = 4 and since the focus is below the directrix, p is negative, i.e. p = -4 Equation of a parabola is given by (x - h)^2 = 4p(y - k) Therefore, the required equation is (x - 0)^2 = 4(-4)(y - 0) x^2 = -16y y = -1/16 x^2
