Sum of Two Odd Powers/Examples/Sum of Two Cubes/Proof 2

Proof
From Sum of Two Odd Powers:


 * $a^n + b^n = \paren {a + b} \paren {a^{n - 1} - a^{n - 2} b + a^{n - 3} b^2 - \dotsb + a b^{n - 2} + b^{n - 1} }$

Setting $n = 3$ gives the result.