You can put this solution on YOUR website! The domain for f(x) is R = all real numbers
The domain for g(x) is R = all real numbers
(fog)(x) = (x-1)+1 = x
(gof)(x) = (x+1)-1 = x
Please note that fog(x) means in f(x) = x+1 You have to replace x with g(x). If you do that you will get (fog)(x) = (x-1)+1 = x