How do you find the equation of the parabola vertex at the origin and the directrix at x=7?

1 Answer
Jan 10, 2016

Answer:

With a vertex #=(0,0)# and directrix #x=7#, this parabola opens to the left and will be of the form #x=(1/(4c))(y-k)^2+h#

Explanation:

The absolute distance between the directrix and vertex #c=7-0=7#

So, the coefficient #1/(4c)=1/(4xx7)=1/28#

The sign of the coefficient must be NEGATIVE because the parabola opens to the left.

vertex #=(0,0)=(h,k)#

Finally, substitute the values into the equation ...

Equation : #x=(-1/(28))(y-0)^2+0=-(y^2)/28#

hope that helped

enter image source here