X^2 + Y^2 + 2mX - 2nY = 0
Then ,complete squares for X and Y by adding m,n terms
Write
( X^2 + 2mX + A ) + (Y^2 - 2nY + B ) = 0 + A + B
Now
(X^2 + 2mX + m^2 ) + (Y^2 -2nY + n^2) = 0 + m^2 + n^2
( X + m)^2 + ( Y - n )^2 = m^2 + n^2
THEN Answer IS
Center of circle is at = ( -m, n)
Radius R is = √m^2 + n^2
NOW graph this circle