SOLUTION: Hello, can you please show me how to do the work for this question: What is the center for the circle represented by the equation x^2+y^2-4x+2y-4=0?

Algebra ->  Formulas -> SOLUTION: Hello, can you please show me how to do the work for this question: What is the center for the circle represented by the equation x^2+y^2-4x+2y-4=0?      Log On


   

Question 771962: Hello, can you please show me how to do the work for this question: What is the center for the circle represented by the equation x^2+y^2-4x+2y-4=0?
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2%2By%5E2-4x%2B2y-4=0
write it first in the standard form: %28x+-+h%29%5E2+%2B+%28y-k%29%5E2+=+r%5E2 where h is x-coordinate and k is y-coordinate of the center (h,k) and r is a radius

%28x%5E2-4x%29%2B%28y%5E2%2B2y%29=4...complete square

%28x%5E2-4x%2B_%29%2B%28y%5E2%2B2y%2B_%29=4
%28x%5E2-4x%2B4%29-4%2B%28y%5E2%2B2y%2B1%29-1=4
%28x-2%29%5E2%2B%28y%2B1%29%5E2-5=4
%28x-2%29%5E2%2B%28y%2B1%29%5E2=9+
so, the center is at (h,k)=(2,-1)
and radius r=3