Write the equation of a parabola with directrix y=8 and focus (0,0)

9514 1404 393

  y = -1/16x^2 +4

Step-by-step explanation:

The vertex is halfway between the focus and directrix, so is at (0, 4). The focus is 4 units below the vertex, so "p" = -4. For vertex (h, k) and focus-vertex distance p, the equation is ...

  y = 1/(4p)(x -h)^2 +k

Using the values we determined, this is ...

  y = -1/16x^2 +4

answer: -2+√x,-2-√x

i hope this , i don't know if you're looking for a pair or not.