Making y the subject of an equation

In an implicit differentiation question (This is the 4th equation I'm doing these steps for but all have been just 3 terms, not 5), it asks:

for the equation x^2 + y^2 - 2x - 4y - 4 = 0;

i) find dy/dx by implicit differentiation
Which I have done, and found dy/dx = (1-x)/(y-2).

ii) by solving the equation for y, find the two functions defined by the equation.
I'm struggling with this one, I've got as far as y^2 - 4y = - x^2 + 2x + 4 and can't work out how to get any further with this.

The next two parts I think are doable once I know how to do ii.
iii) find the derivative of each of the functions found in ii)
iv) verify the results obtained in i) and iii) are in agreement

Thanks in advance.