a⁴b + ab⁴ = ab(a³ + b³) = ab(a + b)(a² - ab + b²)
(a+b)² - (a-b)² = (a+b+a-b)(a+b-(a-b)) = (2a)(2b) = 4ab
a⁴b + ab⁴ = ab(a³ + b³) = ab(a + b)(a² - ab + b²)
2(a+b)² - (a-b)² = (a+b+a-b)(a+b-(a-b)) = (2a)(2b) = 4ab