f(x) = (√1-2x)/(x^2 -9) + 3/(x^2 - 6x +8)

I thought:

x^2-9 -> (x-3)(x+3)

x^2-6x+8 -> (x-4)(x-2)

(√1-2x) (x-4)(x-2) + 3(x-3)(x+3)

---------------------------------------

(x-3)(x+3)(x-4)(x-2)

I just don't know what to do next and it just feels not right , please someone tell me how can I find the domain.