MathDB
Integral inequality

Source: 2023 4th OMpD LU P4 - Brazil - Olimpíada Matemáticos por Diversão

September 21, 2023
calculusinequalitiesintegrationfunction

Problem Statement

Let n0n \geq 0 be an integer and f:[0,1]Rf: [0, 1] \rightarrow \mathbb{R} an integrable function such that: 01f(x)dx=01xf(x)dx=01x2f(x)dx==01xnf(x)dx=1\int^1_0f(x)dx = \int^1_0xf(x)dx = \int^1_0x^2f(x)dx = \ldots = \int^1_0x^nf(x)dx = 1 Prove that: 01f(x)2dx(n+1)2\int_0^1f(x)^2dx \geq (n+1)^2