Question

Find the standard form of the equation of the parabola with a focus at (-4, 0) and a directrix at x = 4.

Answer 1

@zepdrix @TuringTest @jim_thompson5910 @bibby @cwrw238 @satellite73 @Hero @campbell_st @nincompoop @Concentrationalizing

Answer 2

ok... so have you sketched the information you have been given.

It will give you some big clues...

Answer 3

I don't really remember how to

Answer 4

Well, you have to understand the relationship between the directrix and the focus. You dont have to sketch too much, all you need to do is sketch the line x = 4 and the focus, (-4,0). Having these two things graphed will orient you and tell you the direction the parabola is facing. If you are facing up, you have a standard form of (x-h)^2 = 4p(y-k). Facing down just means you have an extra negative sign on the outside. Facing right means you have the standard form (y-k)^2 = 4p(x-h). Facing left just means you have an extra negative sign on the outside. Do you know about where the focus, directrix are in relationship to the parabola? And do you know what the value of p means in the standard form equation? If you do, then its just finding the direction your facing, the center, and the value of p and plugging them in.