It's been known for hundreds of years that this is not possible. Euler gave a proof in 1770:<p><a href="http://fermatslasttheorem.blogspot.com/2005/05/fermats-last-theorem-proof-for-n3.html" rel="nofollow">http://fermatslasttheorem.blogspot.com/2005/05/fermats-last-...</a><p>See also: <a href="http://en.wikipedia.org/wiki/Fermat%27s_Last_Theorem" rel="nofollow">http://en.wikipedia.org/wiki/Fermat%27s_Last_Theorem</a>