2. In this question, preferences are given by a binary relation on the consumption set which is assumed to be the closed first quadrant in the plane (so that there are two commodities called X and Y, with quantities written as x and y respectively). (30 points total) (a) Define the concept of a preference relation being represented by a utility function. What functions can be utility functions? (5 points) (b) Describe an example of preferences that cannot be represented by a utility function. What assumption do these preferences violate which ca uses there to be no utility representation? (5 points)