MathDB
inequality

Source: 48th Austrian Mathematical Olympiad Beginners' Competition(2017)

February 27, 2018
inequalitiesalgebraAustria

Problem Statement

The nonnegative real numbers aa and bb satisfy a+b=1a + b = 1. Prove that:
12a3+b3a2+b21\frac{1}{2} \leq \frac{a^3+b^3}{a^2+b^2} \leq 1
When do we have equality in the right inequality and when in the left inequality?
Proposed by Walther Janous