MathDB
Easy rationality

Source: LIMIT 2020 Cat 1 Obj P1

May 2, 2020
irrationallimit

Problem Statement

If aa is a rational number and bb is an irrational number such that abab is rational, then which of the following is false?
(A)ab2ab^2 is irrational (B)a2ba^2b is rational (C)ab\sqrt{ab} is rational (D)a+ba+b is irrational