Looking for reference/link to older proofs

[TheAbdicatedKing]

I am looking for three proofs of X^n - Y^n = (X-Y)((X^(n-1))Y^2+...+X^2(Y^(n-1))).

The 1st by Fermat which was disproved, the 2nd by Pascal which was considered to have gaps but not disproved and the 3rd by Euler which has been accepted as correct.

Any help is appreciated.