MathDB
int f(x)g(x) dx <= int f(x)g(1-x) dx

Source: 1980 Swedish Mathematical Competition p4

March 28, 2021
integrationanalysisinequalities

Problem Statement

The functions ff and gg are positive and continuous. ff is increasing and gg is decreasing. Show that 01f(x)g(x)dx01f(x)g(1x)dx \int\limits_0^1 f(x)g(x) dx \leq \int\limits_0^1 f(x)g(1-x) dx