SOLUTION: I need help in writing an equation for a parabola with vertex at (4,-1) and directrix y = 1. Thank you

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Question 442284: I need help in writing an equation for a parabola with vertex at (4,-1) and directrix y = 1. Thank you
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

parabola with vertex at (4,-1) and directrix y = 1.

Directrix parallel to the x-axis. Parabola opening upward or downward.

Note: standard form is %28x+-h%29%5E2+=+4p%28y+-k%29, where  the focus is (h,k + p)

and the directrix is -p distance from the vertex

vertex at (4,-1) directrix y = 1 Parabola opens downward

 (x-4)^2 = -8(y+1)  |directrix y = 1 therefore: p = -2  4p = -8 

or y = (-1/8)(x-4)^2 - 1









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