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| Question 552468:  what is the focus of this conic section
 9x^2+25y^2-200y+175=0
 Answer by lwsshak3(11628)
      (Show Source): 
You can put this solution on YOUR website! what is the focus of this conic section 9x^2+25y^2-200y+175=0
 complete the square
 9x^2+25(y^2-8y+16)=-175+400
 9x^2+25(y-4)^2=225
 x^2/25+(y-4)^2/9=1
 This is an equation of an ellipse with horizontal major axis of the standard form:
 (x-h)^2/a^2+(y-k)^2/b^2=1, a>b, (h,k) being the (x,y) coordinates of the center.
 For given equation:
 Center: (0,4)
 a^2=25
 b^2=9
 c^2=a^2-b^2=25-9=16
 c=√16=4
 Foci: (0±c,4)=(0±4,4)=(-4,4) and (4,4)
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