Answer:
(x + y)(x² - xy + y²)(x + 1)
Explanation:
Given
+ xy³ + x³ + y³ ( factor out x from the first 2 terms )
= x(x³ + y³) + 1(x³ + y³) ← factor out (x³ + y³) from each term
= (x³ + y³)(x + 1)
x³ + y³ is a sum of cubes and factors as (x + y)(x² - xy + y²)
Thus
+ xy³ + x³ + y³ = (x + y)(x² - xy + y²)(x + 1)