Bionomials.....sums of cubes???

Question

Sums and differences of cubes??

Factor Completly:

1) 3z^5 - 3z^2

2) a^9 + b^12 c^15

Answer 1

1) 3z^5-3z^2 = 3z^2(z^3-1) = 3z^2 (z^3-1^3) now use the formula for difference of cubes.
2) a^9+b^12c^15 = (a^3)^3 + (b^4c^5)^3 Now use sum of cubes formula.