1. The problem statement, all variables and given/known data Definition:. Let A and B be sets. The Cartesian product AXB of A and B is the set of ordered pairs (a, b) (3) Assume that A and B are countable sets. Prove that the Cartesian product A x B is countable. 2. Relevant equations 3. The attempt at a solution I know that to prove that something is countable, you need to check if the function is a bijection, which I know how to do. However, I am having a little trouble understanding what the function for this question would be. Would it be: f:AxB------>AxB where f(AxB)=(A,B)?