# Definition of a Polynomial

The formal definition, according to Wikipedia, is "an expression consisting of variables and coefficients which only employs the operations of addition, subtraction, multiplication, and non-negative integer exponents."

Ok, that probably didn't help, did it? What does it really mean? Well, a polynomial is something that looks like this:

$$x^2+7x-9$$

It contains variables ($$x$$), it uses multiplication, subtraction, and addition, and has a positive, integer exponent (the $$x^2$$ term).