F(5,0) directrix y=-4

Question

F(5,0) directrix y=-4

 

Answer 1

The vertex is midway between the focus and directrix......so it has coordinates (5,-2). p is the directed distance from the vertex to the focus which is +2

 

So, by substituting this information into the formula of a parabola with a horizontal directrix, which is

(x-h)² = 4p(y-k) you get your answer of (x-5)² = 8(y+2). 

 

There are other forms of this general equation, so make sure you use the one that your teacher is using.

Hope this helped.

Answer 2