Use the definition, A real number x is said to be rational if there exist integers y and z, z0, such that x=y/z.

Use the definition, A real number x is said to be rational if there exist integers y and z, z≠0, such that x=y/z. A number is said to be irrational if it is not rational and prove this statement by contraposition. For all real numbers x and y, if xy is an irrational number then x is an irrational number or y is an irrational number.