MathDB
Easy algebra on 4 positive reals

Source: Caucasus MO 2024, Seniors P1

March 15, 2024
algebra

Problem Statement

Let a,b,c,da, b, c, d be positive real numbers. It is given that at least one of the following two conditions holds: ab>min(cd,dc),cd>min(ab,ba).ab >\min(\frac{c}{d}, \frac{d}{c}), cd >\min(\frac{a}{b}, \frac{b}{a}). Show that at least one of the following two conditions holds: bd>min(ca,ac),ca>min(db,bd).bd>\min(\frac{c}{a}, \frac{a}{c}), ca >\min(\frac{d}{b}, \frac{b}{d}).