# Thread: Equation of a parabola

1. ## Equation of a parabola

I have to write the equation in standard form for the parabola with an axis of symmetry y=0 and focus (-5,0). I have no idea where to start with this one although I know the formula for the standard form of a parabola equation. I also know the focus and vertex are on the axis of symmetry. I do not know how to apply this information to the problem.

Thanks.

2. ok... an axis of symmetry is the X value of the vertex. Also the formula to find the axis of symmetry with a given quadratic equation(parabola) is -b/2a.

See where you can get with that

3. Originally Posted by Joanie
I do not know how to apply this information to the problem.
I don't believe the equation can be found with only the listed information, since we don't know on which side of the focus is the vertex, etc. I think we need one more piece of information.

(Note: The axis of symmetry provided the x-coordinate of the vertex only if that axis is vertical. This one is not.)