Quadratic equations and cubic equations are examples of polynomials.

A polynomial in x is of the form:

$p(x)=ax^n+bx^{n-1}+cx^{n-2}+...+px+q$

Solving $p(x)=0$ will give n roots, some (or all) of which might be complex (see complex number), although some may be repeated roots. For example, $x^2-2x+1=0$ has two roots, but both are equal to 1.