a² - b² = (a - b)(a + b)
(a + b)² = a² + 2ab + b²
(a² - b²)² / (a² + 2ab + b²) = ((a - b)(a + b))² / (a + b)² = (a - b)²(a + b)²/(a + b)² = (a - b)² = a² - 2ab + b²
a² - b² = (a - b)(a + b)
(a + b)² = a² + 2ab + b²
(a² - b²)² / (a² + 2ab + b²) = ((a - b)(a + b))² / (a + b)² = (a - b)²(a + b)²/(a + b)² = (a - b)² = a² - 2ab + b²