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

12x420x2+13\displaystyle {12}{x}^{{4}}-{20}{x}^{{2}}+{13} is

20x8+8x63x2+5\displaystyle {20}{x}^{{8}}+{8}{x}^{{6}}-{3}{x}^{{2}}+{5} is

8x3+5\displaystyle {8}{x}^{{3}}+{5} is

20x4+8x38x2+3\displaystyle {20}{x}^{{4}}+\frac{{8}}{{x}^{{3}}}-{8}{x}^{{2}}+{3} is

9x4\displaystyle {9}{x}^{{4}} is