Question

Simplify:
(3a + 2b - c)(9a² + 4b² + c² - 6ab + 2bc +3ca)

Answer 1

(3a + 2b - c)(9a² + 4b² + c² - 6ab + 2bc +3ca)
= 3a(9a² + 4b² + c² - 6ab + 2bc + 3a) + 2b (9a² + 4b² + c² - 6ab + 2bc + 3ca) - c(9a² + 4b² + c² - 6ab + 2bc + 3ca)
= 27a³ + 12ab² + 3ac² - 18a²b + 6abc + 9a²c + 18a²b + 8b³ + 2bc² - 12ab² + 4b²c + 6abc - 9a²c - 4b²c - c³ + 6abc - 2bc² - 3ac²
= 27a³ + 8b³ - c³ + 18abc.