1️⃣和立方与差立方
(a+b)³ = a³ + 3a²b + 3ab² + b³
(a-b)³ = a³ - 3a²b + 3ab² - b³
2️⃣立方和与立方差
a³+b³ = (a+b)(a²-ab+b²)
a³-b³ = (a-b)(a²+ab+b²)