Let <I>F</I> be a field and
 <i>p</i>(<i>x</i>)
  be irreducible polynomial of degree <I>n</i> over <I>F</i>.  If <I>a</i> is a zero of
 <i>p</i>(<i>x</i>)
  in some extension 
<I>E</i> 
of <I>F</i>, describe the elements of the field
<I>F</i>(<I>a</i>).