MathDB
Manipulating Polynomials

Source: Tournament of Towns Sprin 2016

February 22, 2017
combinatoricsalgebrapolynomialinvariant

Problem Statement

On a blackboard, several polynomials of degree 3737 are written, each of them has the leading coefficient equal to 11. Initially all coefficients of each polynomial are non-negative. By one move it is allowed to erase any pair of polynomials f,gf, g and replace it by another pair of polynomials f1,g1f_1, g_1 of degree 3737 with the leading coefficients equal to 11 such that either f1+g1=f+gf_1+g_1 = f+g or f1g1=fgf_1g_1 = fg. Prove that it is impossible that after some move each polynomial on the blackboard has 3737 distinct positive roots. (8 points)
Alexandr Kuznetsov