Yes. A monomial is a term composed by a coefficient and powers of variables multiplied with each other, for example
[tex]3xy^3z^2[/tex]
is a monomial.
In your case, the monomials are
[tex]9,\quad 8x^2,\quad 2x^4[/tex]
As the name suggests, a trinomial is the sum of three monomials, which is exactly your case.
