4a³ + 2b³ - 2a²b - 4ab² = 2a³(2 + b) - 2b(a² + 2ab) = 2a³(2 + b) - 2b(a(a + 2b)) = 2a³(2 + b) - 2ab(a + 2b) = 2a³(2 + b) - 2ab(2a + b)