5. Let f be twice differentiable on (a,b). If g is an antiderivative of f" on (a,b), then g’(x) must equal

 

A. f(x)

B. f’(x)

C. f"(x)

D. f’(x) + C, for some C not necessarily 0

E. f"(x) + C, for some C not necessarily 0

 

Solution: The answer is C

 

By definition, a function g is called an antiderivative of f" on (a,b) if g’(x) = f"(x) for all x in (a,b).