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Identify the equation of the parabola with its focus at (-4,9) and the directrix y=-3. 

A) 24(y-7)=(x+4)^2 

B) -12(y+4)=(x+4)^2 

C) 24(y-3)=(x+4)^2 

D) 12(y-4)=(x+4)^2

 Jun 26, 2016
 #1
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In the form  (x - h)2  = 4p (y - k)

 

The vertex, (h,k)  will be (-4, 3)     and  p  can be found by subtracting the y coordinate of the vertex  from the y coordinate of the focus   =  [9  - 3]    = 6

 

So we have

 

(x + 4)2  =  4 (6)(y - 3)

 

(x + 4)2 = 24(y - 3)    which is the same as

 

24(y - 3) = (x + 4)2

 

 

 

cool cool cool

 Jun 26, 2016

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