Polynomial Functions

The general form of quadratic functions will be as the form. $f(x)=a_{n}x^{n}+a_{n-1}x^{n-1}+a_{n-2}x^{n-2}+....+a_{2}x^{2}+a_{1}x+a_{0}$ But need to remember that $a_{n}$ , $a_{n-1}$ ......$a_{1}$ and $a_{0}$ they can all be 0