MathDB
3-variable inequality with squares

Source: Italy MO 2023 P5

May 7, 2023
algebrainequalities proposed

Problem Statement

Let a,b,ca, b, c be reals satisfying a2+b2+c2=6a^2+b^2+c^2=6. Find the maximal values of the expressions a) (ab)2+(bc)2+(ca)2(a-b)^2+(b-c)^2+(c-a)^2; b) (ab)2(bc)2(ca)2(a-b)^2 \cdot (b-c)^2 \cdot (c-a)^2. In both cases, describe all triples for which equality holds.