The polynomial is x^n + A1x^(n-1) + A2x^(n-2) + ... + A2x^2 + A1x + 1. Where An (integer) is not zero for all n and n is even. For example: x²+x+1; x^4+2x^3+3x^2+2x+1. I'm looking for a method to say if that kind of polynomial is irreducible over racionals... Or when it is. Thx!