To determine whether the given expression is a polynomial, recall that a polynomial is a monomial or the sum of monomials.
A monomial is either a number, a variable, or an expression that is the product of one or more variables with non-negative integer exponents.
Consider the given expression.
7ab+6b^2-2a^3
This expression is a polynomial because each term is a monomial. The degree of a polynomial is the degree of the monomial with the greatest degree. For our polynomial, the degree is 3. Also, it is a sum of the three monomials, so it is a trinomial.
