MathDB
Inequality problem with max and min

Source: 2022 China Second Round A2

December 22, 2022
inequalities

Problem Statement

a1,a2,...,a9a_1,a_2,...,a_9 are nonnegative reals with sum 11. Define SS and TT as below: S=min{a1,a2}+2min{a2,a3}+...+9min{a9,a1}S=\min\{a_1,a_2\}+2\min\{a_2,a_3\}+...+9\min\{a_9,a_1\} T=max{a1,a2}+2max{a2,a3}+...+9max{a9,a1}T=\max\{a_1,a_2\}+2\max\{a_2,a_3\}+...+9\max\{a_9,a_1\} When SS reaches its maximum, find all possible values of TT.