SOLUTION: Find the center of a circle with the equation x2 + y2 + 2x + 4y – 9 = 0.

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Question 322575: Find the center of a circle with the equation x2 + y2 + 2x + 4y – 9 = 0.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Complete the square in x and y,
x%5E2+%2B+y%5E2+%2B+2x+%2B+4y-9=0
%28x%5E2%2B2x%2B1%29%2B%28y%5E2%2B4y%2B4%29-9=1%2B4
%28x%2B1%29%5E2%2B%28y%2B2%29%5E2=14
Compare to the general equation of a circle centered at (h,k) with radius R,
%28x-h%29%5E2%2B%28y-k%29%5E2=R%5E2
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(h,k)=(-1,-2)