Precalculus: Functions

Problem : Let set A = {1, 2, 3} and set B = {4, 5} . What is their Cartesian product A×B ?

Problem : What is the Cartesian product of the set of real numbers and itself?

Problem : What is the Cartesian product of the set of positive real numbers with itself?

Problem : What is the domain and range of the relation {(2, 4),(4, 8),(8, 16)} ?

Problem : What is the domain and range of the relation y = ± ?