MathDB
IMC 2011 Day 2, Problem 4

Source:

August 1, 2011
algebrapolynomialinductionIMCcollege contests

Problem Statement

Let ff be a polynomial with real coefficients of degree nn. Suppose that f(x)f(y)xy\displaystyle \frac{f(x)-f(y)}{x-y} is an integer for all 0x<yn0 \leq x<y \leq n. Prove that abf(a)f(b)a-b | f(a)-f(b) for all distinct integers a,ba,b.