Find f(g(x))= (fog) (x), and g(f(x))= (gof) (x)
find their domains
F(x)= l x-4 l
Well, you can find (FoG)(x) and (GoF)(x) easily. Simply put G(x) whereever an x is in the F(x), and vice versa for the other one.
The Domain is simply what range of values can be used in each function. Can it be any number or only a limited range of numbers?
The real question is "do you understand what "domain" means?" If you do, then this question is very simple.
Are there any values of x for which you cannot subtract 4 and take the absolute value?
Are there any values of x for which you cannot multiply by 3 and add 2?