Hello,Originally Posted byfreswood

if the vertex of the parabola has the coordinates (z, v) then the equation of the parabola, which you should use, is:

You've got 3 points, which belong to the parabola:

P(0, 10)

V(z, -8)

N(5, 0)

Put in the coordinates of these points into the equation and you'll get:

Solve the 1rst equation for a:

and put it into the 2nd equation. You'll get:

Solve for z. The results are: z=3 or z=15

I've attached a graph to demonstrate these results.

Greetings

EB