Answer:
(a + b + 2c)(a² + 2ab + b² - 2ac - 2bc + 4c²)
Explanation:
Given
(a + b)³ + 8c³ ← this is a sum of cubes and factors in general as
a³ + b³ = (a + b)(a² - ab + b²)
Thus
(a + b)³ + 8c³
= (a + b)³ + (2c)³
= (a + b + 2c)( (a + b)² - 2c(a + b) + (2c)² )
= (a + b + 2c)(a² + 2ab + b² - 2ac - 2bc + 4c²)