Answer:
(11x - 9y) (121x² + 99xy + 81)
Step-by-step explanation:
Difference of cubes
∛1331x³ = 11x = a
∛729y³ = 9y = b
(a³ + b³) = (a + b) (a² - ab + b²)
(a³ - b³) = (a - b) (a² + ab + b)
(1331x³ - 729y³) = (11x - 9y) (121x² + 99xy + 81)