Posted by Anonymous on Saturday, September 5, 2009 at 2:16pm.
What are the coordinates of the center of a circle with the equation x^26x+y^2+4y=20?
All help is appreciated.

Math  MathMate, Saturday, September 5, 2009 at 3:00pm
The centre of the circle
C : (xx1)² + (yy1)² = r²
is at (x1,y1).
For the given circle, the centre can be found by completing the squares, namely:
x^26x+y^2+4y=20
(x3)²9 + (y+2)²4 = 20
(x3)² + (y+2)² =33
Can you find the centre of the circle?