Calculus

Are the following statements true or false? ? C 1. The set of all a's that are in the domain of g and in the domain of f and where f(x) # 0 correctly describes the domain of * (x). C 2. The set of all x's that are in the domain of g and where g(a) is in the domain of f correctly describes the domain of f(g(x)). ? 3. If f(a) = 5, then f(a t h) = 5. ? C 4. If x is in the domain of g, then a is in the domain of (f + g) (x). ? 5. The domains of (f + g) (x) , (f - g) (x) and (f . g) (x ) are all the same. ? 6. (f . g) (a) = f(a) . g(a) as long as a is in both the domain of f and in the domain of g