SOLUTION: Find the center and radius of x^2+y^2-x+2y+1=0

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Question 693439: Find the center and radius of x^2+y^2-x+2y+1=0
Answer by pmatei(79) About Me  (Show Source):
You can put this solution on YOUR website!
This is solved by completing the squares:
x%5E2%2By%5E2-x%2B2y%2B1=0
x%5E2-x+%2B%28y%5E2%2B2y%2B1%29=0
x%5E2-2%2A%281%2F2%29%2Ax%2B%281%2F2%29%5E2-%281%2F2%29%5E2%2B%28y%2B1%29%5E2=0
%28x-1%2F2%29%5E2%2B%28y%2B1%29%5E2=%281%2F2%29%5E2
Compare to %28x-x%5B0%5D%29%5E2%2B%28y-y%5B0%5D%29%5E2=r%5E2 where x%5B0%5D ,y%5B0%5D are the coordinates of the circle's center and r is the radius.
The center of the circle is at x%5B0%5D=1%2F2, y%5B0%5D=-1 and the radius is r=1%2F2.