A parabola has a vertex at the origin. The focus of the parabola is located at (–2,0).

Which is the equation for the directrix related to the parabola?

Question

A parabola has a vertex at the origin. The focus of the parabola is located at (–2,0).



Which is the equation for the directrix related to the parabola?

mathmale · Answer

The directrix is the same distance from the vertex as is the focus from the vertex.

mathmale · Answer

Weren't there answer choices here?  If so, please share them.

mathmale · Answer

You need to figure out what the parabola would look like.  Will it open UP?  Down?  To the left?  To the right?  How do you know that?

preneisha · Answer

parabola?


y = 2

x = 2

y = –2

x = –2

mathmale · Answer

Four answer choices.  Great.  Now, in which direction does your parabola open?

preneisha · Answer

it doesn't say the problem only ask Which is the equation for the directrix related to the parabola

mathmale · Answer

If you figure out how the vertex, directrix and focus are positioned with respect to one another, you will find it much easier to answer this question.  

Look up "focus of a parabola."  I'd bet you'll find one or more diagrams that show you examples of this positioning.