(a² + 2ab + b²)-(c² - 4cd + 4d²) = (a + b)² - (c - 2d)² = (a + b - (c - 2d))(a + b + c - 2d) = (a + b - c + 2d)(a + b + c - 2d)
(a² + 2ab + b²)-(c² - 4cd + 4d²) = (a + b)² - (c - 2d)² = (a + b - (c - 2d))(a + b + c - 2d) = (a + b - c + 2d)(a + b + c - 2d)