Determine whether each expression is a polynomial. If so, identify the polynomial as a monomial, binomial, or trinomial.

$3b^2$

A monomial is a number, a variable or the product of a number and one or more variables with non-negative integer exponents. The monomial has only one term.

A polynomial is a monomial or the sum of monomials, each called a term of the polynomial.

The polynomial having only one term is called a monomial.

The polynomial having two terms is called a binomial. That is binomial is sum of two monomials.

The polynomial having three terms is called a trinomial. That is trinomial is sum of three monomials.

The given expression is$3b^2$.

It can be noticed that the term of the given expression is the product of a number and one variable with non-negative integer exponents.

Therefore, the term of the given expression is a monomial.

As, the given expression is the monomial. Therefore, the given expression is a polynomial.

The given expression is a polynomial having only one term.

Therefore, the given polynomial $3b^2$is a monomial.