How do you find the center and radius of the circle given x2+y2+6y=−50−14x?

1 Answer
Mark D.
Apr 18, 2018

Centre (-7,-3) radius √8

Explanation:

(x−a)2+(y−b)2=r2 is the standard form for the equation of a circle with (a,b) the centre and radius r

Rearrange to this form:
x2+14x+y2+6y=−50

Complete the square:
[(x+7)2−49]+[(y+3)2−9]=−50

(x+7)2+(y+3)2=−50+58

Collect terms and tidy up
(x+7)2+(y+3)2=8

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