What is the equation of a parabola with a vertex at (1, -1) and a directrix y = 4.

http://picpaste.com/pics/Screen_Shot_2014-10-27_at_8.33.27_PM-4L9Al2pD.1414467267.png

Question

What is the equation of a parabola with a vertex at (1, -1) and a directrix y = 4.

http://picpaste.com/pics/Screen_Shot_2014-10-27_at_8.33.27_PM-4L9Al2pD.1414467267.png

anonymous · Answer

you know what this one looks like (no one likes these conic section questions but they are not that hard)

tkhunny · Answer

Vertex at (1,-1) - The fourth one is done.  Wrong Vertex.
Directrix y = 4.  That's above the vertex, so this needs a negative leading coefficient and it's horizontal, so x^2, not y^2 - The second one is no good.  Wrong sign.
Distance from Vertex to Directrix is 4. -- The third one is no good.  Wrong directrix.

Study your properties.  They will serve you well.