MathDB
(ax + b)/x=(Ax + B)/Cx \in Q (HOMC 2013 J Q15)

Source:

July 28, 2019
rationalalgebra

Problem Statement

Denote by QQ and NN^* the set of all rational and positive integer numbers, respectively. Suppose that ax+bxQ\frac{ax + b}{x} \in Q for every xNx \in N^*: Prove that there exist integers A,B,CA,B,C such that ax+bx=Ax+BCx\frac{ax + b}{x}= \frac{Ax + B}{Cx} for all xNx \in N^*