my favorite theorem is Fermat's Last Theorem because this theorem had not been proved over 350 years. but finally in 1993, in England, one of the mathematician, Andrew Wiles, proved it. when he was young, he touched this theorem. And he determined he would prove this theorem for his life goal. and finally he proved it. When i get a stuck with math problem, i think this happen for having energy for not giving up. Fermat's Last Theorem is the name of the statement in number theory that:
It is impossible to separate any power higher than the second into two like powers, or, more precisely:
If an integer n is greater than 2, then the equation a n + b n = c n has no solutions in non-zero integers a, b, and c