It looks like it should be what you said except for one minor mistake, but heres a tip that will help you with the first and 2nd making life easier.

Ok first off:

Recognize the common factor here 12x, personally I would pull out a -12x

thus becoming this become an easily visible factor(depending on your math level) : we find ourselves with 3 equations :

12x x+1 x-2

I don't see where you got the answer -12, I see 0 though,

Pulling out an gives you a completely different equation then the original, wouldn't it.. Im no professional but I can factor and I don't see how -12 could be an answer