Formula for roots of higher polynomials?

Does anyone know of the formulas for roots of higher order polynomials (3+)?  We learned the quadratic formula in grade school but never heard of formulas for higher polynomials..  do they exist?

>>5
The fact is the A_n is normal for n>5, and thus S_n contains a simple, normal subgroup.

The reason that makes the equations unsolvable, is touched on by the wiki page on "Galois theory", but I'm not entirely certain myself how it follows.