**Question from Renee, **

Please confirm the correct answers for Chapter 9 Lesson 2 on page 403–Problem number 4 (a-f). Answers seem wrong in the answer key. Seems to me they should all be “yes” except “d.” Am I wrong?

**Answer:**

In this problem, you are being asked whether or not each expression is a polynomial.

In lesson 9.2, you have a definition of a polynomial: “A polynomial is either a monomial or an expression indicating the addition and/or subtraction of two or more monomials.”

In lesson 9.1 you see that a monomial is an expression in the form of **ax^n** — **where n is positive.**

**In 4c,** n is negative, and therefore it is not a polynomial.

**In 4f,** you have the form a^x instead as one of the terms, which is not a monomial, and therefore 4f is not a polynomial.