A **polynomial function** is a function that can be written in the form:

f(x) = a

_{n}x^{n}+ a_{n - 1}x^{n - 1}+ ... + a_{1}x + a_{0}

*n*is a nonnegative integer, called the**degree**of the polynomial.- The coefficients
*a*are real numbers with_{0}, a_{1}, ..., a_{n}*a*._{n}≠ 0 - The
**domain**of a polynomial function is the set of all real numbers.

A **rational function** is any function that can be written in the form:

f(x) = n(x)/d(x), d(x) ≠ 0

*n(x)*and*d(x)*are polynomials.- The
**domain**of a rational function is the set of all real numbers such that*d(x) ≠ 0*.