Which is the correct factorization for -3x^5 + 24x^2?
-3x^2(x - 2)(x^2 + 2x + 4)
-3x^2(x - 2)(x + 2)(x + 2)
-3x^5 + 24x^2
factor out -3x^2 and you have
(-3x^2)(x^3) + (-3x^2)(-8)
-3x^2 (x^3-8)
Now recall the factorization of the difference of two cubes, and you have
-3x^2(x-2)(x^2+2x+4)