What is the focus of the parabola (y-9)^2 = -8(x+5)?

1 Answer
May 27, 2017

Focus is at (-7,-9)

Explanation:

(y-9)^2 = -8 (x+5) or (y-9)^2 = -4 *2 (x+5) ; h= -5 , k =9 , a = -2 .

This is a parabola of standard equation (y-k)^2 = -4a (x-h) opening left .

Vertex is at (h,k) i.e ( -5,9) . Focus is at "a" distance left of vertex.

So focus is at (h+a),k or ( (-5-2), 9) or (-7,9)
graph{(y-9)^2=-8(x+5) [-80, 80, -40, 40]} [Ans]