In this article, we consider the polynomials of the form
![$f(x)=a_0+a_1x+a_2x^2+\cdots+a_nx^n\in \Z[x],$](img40.png)
where

and

is a prime.
We show that these polynomials have a cyclotomic factor whenever reducible. As a consequence, we give a simple procedure for checking the irreducibility of trinomials of this form and separability criterion for certain quadrinomials.