MathDB
Polynomial - odd or even coefficients

Source: Romanian TST 2 2007, Problem 1

April 15, 2007
algebrapolynomialalgebra proposed

Problem Statement

Let f=Xn+an1Xn1++a1X+a0f = X^{n}+a_{n-1}X^{n-1}+\ldots+a_{1}X+a_{0} be an integer polynomial of degree n3n \geq 3 such that ak+anka_{k}+a_{n-k} is even for all k1,n1k \in \overline{1,n-1} and a0a_{0} is even. Suppose that f=ghf = gh, where g,hg,h are integer polynomials and deggdegh\deg g \leq \deg h and all the coefficients of hh are odd. Prove that ff has an integer root.