How do i factor this problem completely?

Question

216x^3 - y^3

Answer 1

recall that a^3-b^3 = (a-b)(a^2+ab+b^2)
You have

(6x)^3 - y^3
= (6x-y)((6x)^2 + (6x)y + y^2)
= (6x-y)(36x^2 + 6xy + y^2)