how to solve 7x^2+7y^2-28x+63y-4=0 in general equation of circle?

Answer 1

not sure what you mean by "solve"
If you want to find the center and radius, complete the squares:
7x^2+7y^2-28x+63y-4 = 0
7(x^2-4x+4) + 7(y^2+9y+(9/2)^2) = 4 + 7*4 + 7(9/2)^2
7(x-2)^2 + 7(y + 9/2)^2 = 695/4
(x-2)^2 + (y + 9/2)^2 = 695/28
now you can read off the center and radius