MathDB
There exists an integer

Source: NMTC 2019 Junior P2

November 2, 2019
number theory

Problem Statement

Given positive real numbers a,b,c,da, b, c, d such that cd=1cd=1. Prove that there exists at least one positive integer mm such that abm2(a+c)(b+d).ab\le m^2\le (a+c) (b+d).