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

A×B = {(1, 4),(1, 5),(2, 4),(2, 5),(3, 4),(3, 5)}. This is every possible ordered pair from which the first element is taken from A and the second element taken from B.

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

The Cartesian product is every ordered pair in the coordinate plane.

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

The Cartesian product is every ordered pair in the first quadrant of the coordinate plane.

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

Domain D = {2, 4, 8}. Range R = {4, 8, 16}.

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

Domain D is real numbers > 0. Range R is all real numbers.