2. Consider the expected utility function U(21, 12) = mu(21) + 2u(12). The properties of this function depend on the properties of the underlying function u. (a) Give the definition of concave function. Give an example of a concave function u. Explain how you know the function is concave, and how you know a person who maximizes expected utility with such an underlying function u is risk averse. (b) Repeat your answer to (a) for the case of a convex function and risk seeking behavior