In this paper, it is established that a necessary and sufficient condition for two monic polynomials

and

to have a common root is that
![\\det [f(B)] = 0](/images/tex/5568.gif)
or
![\\det [g(A)] = 0](/images/tex/5569.gif)
, where

and

are, respectively, the companion matrices associated with

and

. The simplicity of this method is illustrated by examples.