MathDB
China Northern Mathematical Olympiad 2023 , Problem 4

Source: China 10 Aug

August 11, 2023
inequalitiesalgebraminimuminequalities proposed

Problem Statement

Given the sequence (an)(a_n) satisfies 1=a1<a2<a3<<an1=a_1< a_2 < a_3< \cdots<a_n and there exist real number mm such that i=1n1ai+1ai(2+ai)43m\displaystyle\sum_{i=1}^{n-1} \sqrt[3]{\frac{a_{i+1}-a_i}{(2+a_i)^4}}\leq m for any positive integer n n not less than 2 . Find the minimum of m.m.