MathDB
for any m, n in Z there exists a k in Z such that f(k) = f(m) - f(n).

Source: 2015 Saudi Arabia BMO TST II p1

July 24, 2020
algebrafunctional equationfunctionalfunctionIncreasing

Problem Statement

Find all strictly increasing functions f:ZRf : Z \to R such that for any m,nZm, n \in Z there exists a kZk \in Z such that f(k)=f(m)f(n)f(k) = f(m) - f(n).
Nguyễn Duy Thái Sơn