# Polynomials

A **monomial** is formed by the product of numbers and letters or variables (with powers). A **polynomial** is the addition or subtraction of monomials. If we only have two monomials, we call it **binomial** and if we have three, we call it **trinomial**.

The **degree of a variable** is the index of its power and the **degree of the monomial** is the addition of the degrees of its variables. The **degree of a polynomial** is the biggest degree of its monomials.

Examples:

· 3x + y is a binomial of degree 1

· x^{2} – 3x + 2 is a trinomial of degree 2

· a + 3b – 5ab + 8abc is a polynomial of degree 3

**Exercise**: decide whether they are polynomials or not and if they are classify them:

a) x^{2}y + 5x^{2}y^{2}

b) 5x/3 + 2xy +7/3

c) 3/x +2x^{2}

Solutions: a) Binomial of degree 4; b) trinomial of degree 2; c) it is not a polynomial