Date: Tue, 21 Jul 1998 20:13:20 -0600 (CST)
Subject: parabolas

Name: Danica

Who is asking: Student
Level: All

Question:
how do you find the focus, vertex, and directrix of 4x-y^2-2y-33=0

Hi Danica,
I think that you should begin by expressing the parabola in standard form. First write

as

Now add one to both sides and the expression becomes

or

This expression can be written as
.
Now you can find the focus, vertex, and directrix in terms of s and t and then express them in terms of x any y using the fact that t = y+1 and s = x-8.

Cheers,
Penny

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