For expressions below that are polynomials, state whether it is a monomial, a binomial, a trinomial, or an other polynomial. Otherwise, select "Not a polynomial".

$\displaystyle {3}{x}^{{8}}+{5}{x}^{{6}}-{18}{x}^{{3}}+{20}$ is Select an answer a monomial a binomial a trinomial an other polynomial Not a polynomial

$\displaystyle {3}{x}^{{4}}+\frac{{8}}{{x}^{{3}}}-{5}{x}^{{2}}+{18}$ is Select an answer a monomial a binomial a trinomial an other polynomial Not a polynomial

$\displaystyle {3}{x}^{{7}}+{2}$ is Select an answer a monomial a binomial a trinomial an other polynomial Not a polynomial

$\displaystyle {2}{x}^{{8}}$ is Select an answer a monomial a binomial a trinomial an other polynomial Not a polynomial

$\displaystyle {13}{x}^{{4}}-{16}{x}^{{3}}+{6}$ is Select an answer a monomial a binomial a trinomial an other polynomial Not a polynomial