ok.
4y = x^2 + 4x + 8
Using the "completing the square rule", you can get:
4y - 4 = x^2 + 4x + 4
4(y-1) = (x+2)^2
To "complete the square", you first divide the value of x (which is 4 here) by two and square it (and you get 4 from that) and that's pretty much it. So you need 4...