x_1y_1 + x_2y_2 + x_3y_3 <1 if x_1 + y_2 = x_2 + y_3 = x_3 + y_1 =1
Source: Mathematics Regional Olympiad of Mexico Center Zone 2014 P2
November 11, 2021
algebrainequalities
Problem Statement
Let , ,, , , and be positive real numbers, such that . Prove that