Hope you are keeping well.

I understand the basic concept of sum/difference of cubes where a^3+b^3 = (a+b)(a^2-ab+b^2) and a^3-b^3 = (a-b)(a^2+ab+b^2)

But I've been thrown a curveball of factorizing

(x-y)^3 - (x+y)^3

now I've been given the solution of

-2y(3x^2+y^2)

without the in-between steps. I don't understand how to get to this answer. Any assistance would be appreciated.

Thank you

Dalmain