MathDB
f_1 (x) f_2 (x) is periodic when f_1 (x), f_2 (x) are periodic

Source: INAMO Shortlist 2015 A1

May 4, 2019
algebrafunctionperiodicperiod

Problem Statement

Function f:RRf: R\to R is said periodic , if ff is not a constant function and there is a number real positive pp with the property of f(x)=f(x+p)f (x) = f (x + p) for every xRx \in R. The smallest positive real number p which satisfies the condition f(x)=f(x+p)f (x) = f (x + p) for each xRx \in R is named period of ff. Given aa and bb real positive numbers, show that there are periodic functions f1f_1 and f2f_2, with periods aa and bb respectively, so that f1(x)f2(x)f_1 (x)\cdot f_2 (x) is also a periodic function.