factor completely

Question

1) 8x^3 + 27y^3

2) u^3 + 125v^3

Answer 1

Note that
1) 8x^3+27y^3 ≡ (2x)^3+(3y)^3
and apply the following identity:
a^3+b^3 = (a+b)(a^2-ab+b^2)
hint: substitute a=2x, b=3y
2) same strategy as the first.