14. Suppose fi(2) is analytic at 20, while f2(2) is non-analytic at zo. Then show that fi(2)+f2(2) is not analytic at zo. Give an example to show that sum of two non-analytic function can be analytic. 15. Suppose f is analytic in a domain D. If f'(2) = 0 for all z E D, then f is constant on D. Will the result hold if we take D to be any set instead of domain?