ANSWER:
A polynomial is an algebraic expression of ordered addition, subtraction, and multiplication made up of variables, constants, and exponents.
Polynomials are made up of finite terms. Each term is an expression that contains one or more of the three elements they are made of variables, constants, or exponents.
In this case, for each term, the variable is x, the constant is 1, and the exponents are 5, 2, and 1, respectively.
This means that we have a sum of monomials, that is, that the expression is a polynomial.