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Series of integrals

Source: CIIM 2023 - Problem 1

September 19, 2023
fractional partinfinite seriesIntegralcalculusintegration

Problem Statement

Determine all the pairs of positive real numbers (a,b)(a, b) with a<ba < b such that the following series k=1ab{x}kdx=ab{x}dx+ab{x}2dx+ab{x}3dx+\sum_{k=1}^{\infty} \int_a^b\{x\}^k dx =\int_a^b\{x\} dx + \int_a^b\{x\}^2 dx + \int_a^b\{x\}^3 dx + \cdots is convergent and determine its value in function of aa and bb.
Note: {x}=xx\{x\} = x - \lfloor x \rfloor denotes the fractional part of xx.