MathDB
Proving Riemann-integrability

Source: Romanian District Olympiad 2014, Grade 12, P1

June 15, 2014
functionfloor functionlimitintegrationreal analysisreal analysis unsolved

Problem Statement

For each positive integer nn we consider the function fn:[0,n]Rf_{n}:[0,n]\rightarrow{\mathbb{R}} defined by fn(x)=arctan(x)f_{n}(x)=\arctan{\left(\left\lfloor x\right\rfloor \right)} , where x\left\lfloor x\right\rfloor denotes the floor of the real number xx. Prove that fnf_{n} is a Riemann Integrable function and find limn1n0nfn(x)dx.\underset{n\rightarrow\infty}{\lim}\frac{1}{n}\int_{0}^{n}f_{n}(x)\mathrm{d}x.