Answer 1

x³ – y³ = (x – y) (x² + xy + y²)

x² + 2xy + y² = (x + y) (x + y)

3x² + 9xy + 6y² = 3(x² + 3xy + 2y²)

= 3 (x + 2y) (x + y)

(x² – y²) = (x + y) (x – y)

`(x^3 - y^3)/(3x^2 + 9xy + 6y^2) xx (x^2 + 2xy + y^2)/(x^2 - y^2)`

= `((x - y)(x^2 + xy + y^2))/(3(x + 2y)(x + y)) xx ((x + y)(x + y))/((x + y)(x - y))`

= `(x^2 + xy + y^2)/(3(x + 2y))`