for example...
x^2-4x-8y-28=0
in solving this kind of problem, first, group the equation like this...
(x^2-4x) - (8y+28) = 0
then, complete the equation like this...
(x^2-4x+4) - (8y+28+4) = 0
how I get this answer? simple...
[1/2(b)]^2 = [1/2(4)]^2 = 4.
after, if you get 4... add 4 to the constant to balance..
then, factor the equation..
(x-2)^2 - (8y+32) = 0
(x-2)^2 - 8(y+4) = 0
that's the final answer...
