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The focus of a parabola is (3,−7) and the directrix is y=−4.

 

 

What is an equation of the parabola?

(A) - (x−3)2=−3(y+10)

(B) - (x−3)2=−1.5(y+5.5)

(C) - (x−3)2=−6(y+5.5)

(D) - (x−3)2=−12(y+10)

Acceptfully  May 29, 2017
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 #1
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The vertex  is  ( 3, -5.5)  = (h, k)

 

And  p  =   -1.5

 

And we have this form

 

4p(y - k)  =  (x - h)^2

 

So.....the equation becomes

 

4(-1.5)(y - -5.5)  = (x  - 3)^2

 

-6 (y + 5.5)  = ( x - 3)^2       "C"  is correct

 

See the graph, here :  https://www.desmos.com/calculator/rgyxi4lf5n

 

 

cool cool cool

CPhill  May 29, 2017

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