Consider the given expression. 4a6−3a3+5a\begin{gathered} 4a^6-3a^3+\dfrac{5}{a} \end{gathered}4a6−3a3+a5 Since monomials cannot contain variables in the denominator, 3a\frac{3}{a}a3 is not a monomial. Therefore, the above expression is not a polynomial in one variable.