Question

(a+b)cube -8(a-b)cube​

Answer 1

Answer:

- 7a³ + 9b³ + 27a²b - 21ab²

Step-by-step explanation:

Given : (a + b)³ - 8(a - b)³

Identity : (a + b)³ = a³ + b³ + 3a²b - 3ab²

(a - b)³ = a³ - b³ - 3a²b + 3ab²

→ a³ + b³ + 3a²b + 3ab² - 8(a³ - b³ - 3a²b + 3ab²)

→ a³ + b³ + 3a²b + 3ab² - 8a³ + 8b³ + 24a²b - 24ab²

→ a³ - 8a³ + b³ + 8b³ + 3a²b + 24a²b + 3ab² - 24ab²

→ - 7a³ + 9b³ + 27a²b - 21ab²