A polynomial is an expression of one variable in the form a n x n + a n-1 x n-1 + ... + a 2 x 2 + a 1 x + a 0 , where a 0, a 1, , a n are real numbers with a n≠ 0 and n is a positive integer. Many real-life situations are easily modeled by polynomial functions. Some of the most familiar are quadratic functions, which are functions of the form f (x) = ax 2 + bx + c . Other polynomial functions are also commonly seen in mathematical models. In the following sections we'll study the general form of polynomials, what a polynomial function looks like, and how to find the roots of a given polynomial function. The roots of a polynomial function are the values of x for which the function equals zero. In a related topic, we'll take a look at rational functions, which are functions that can be written as a quotient of two polynomials. After an in-depth look at polynomial functions, they will be easy to deal with in calculus.