A Solved Problem on Simplification

Topic : Simplification

Problem : Simplify (c + 9)(c³ - 3c² - 7c)

Solution :
(c + 9)(c³ - 3c² - 7c)
= c^4 - 3c³ - 7c² + 9c³ - 27c² - 63c
= c^4 + 6c³ - 34c² - 63c