Consider the integrand h(x)=e2x−5cosx. A one-parameter family of functions is given by
Hk(x)=21e2x−5sinx+kx,
where k is a real constant.
(a) Compute Hk′(x) in terms of k.
(b) Determine the value of k (if any) for which Hk′(x)=h(x) for every real x. Show all algebraic steps leading to your conclusion.
(c) Using the value of k found in part (b), verify explicitly that Hk is an antiderivative of h.
(d) Explain how your result illustrates both the non-uniqueness of antiderivatives and the restriction imposed on k in this particular family.