MathDB
max of xy, weird eq. condition

Source: Moldova 2000 Grade 8 P6

April 25, 2021
Inequalityinequalities

Problem Statement

Assuming that real numbers xx and yy satisfy y(1+x2)=x(14y21)y\left(1+x^2\right)=x\left(\sqrt{1-4y^2}-1\right), find the maximum value of xyxy.