Question 622354
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
the vertex form of a Parabola opening up(a>0) or down(a<0), {{{y=a(x-h)^2 +k}}} where(h,k) is the vertex.
The standard form is {{{(x -h)^2 = 4p(y -k)}}}, where  the focus is (h,k + p)
Parabola with Vertex at origin, focus: (0, -1/4)
 4py = x^2   and p = -1/4, {{{4p = 4(-1/4) = -1}}}
 y = -x^2 
{{{drawing(300,300,   -6, 6, -3, 3,   grid(1),
circle(0, 0,0.2),
circle(0,-.25,0.2),
graph( 300, 300, -6, 6, -3, 3,0,-x^2))}}}