Question

What is the formula of x^n-y^n?​

Answer 1

$x^n - y^n = (x - y)(x^{n - 1}y^0 + x^{n - 2}y^1 + ... + x^1y^{n - 2} + x^0y^{n - 1}$

Note that the overall degree of each term in the second bracket is (n - 1).