Question 760796
2y^2 - 18
2(y^2 - 9)
2(y - 3)(y+ 3)

125z^3 - 27
  (5z - 3)^3

3x^4 - 12y^6
3(x^4 - 4y^6)
3(x^2 - 2y^3)(x^2 + 2y^3)
Hope this helps.
:-)