Answer: a³ - 218
Step-by-step explanation:
(a - 6)(a² + 6a + 36)
= a(a² + 6a + 36) -6(a² + 6a + 36)
= a³ + 6a² + 36a
- 6a² - 36a - 218
= a³ + 0a² + 0a - 218
= a³ - 218
