Answer
This is a polynomial of degree $2$.
Work Step by Step
A monomial is an expression of the form $ax^{k}$,
where $x$ is the variable,
the exponent $k$, a nonnegative integer, is the degree,
and $a$ is the coefficient of the term.
A polynomial expression is either a single monomial or a SUM of several monomials.
The degree of the polynomial is the degree of the monomial with the highest degree.
$10z^{2}$ is a monomial of degree $2$,
$z=1\cdot z^{1}$ is a monomial of degree $1$
Their sum is a polynomial (a binomial).
Thus, the given expression is a polynomial of degree $2$.
