find all zeros, write polynomial as product of linear factors

Question

1) f(x)=9x^3 - x^2 +9x -9
2) f(x)=x^4 -21x^2 -100
3) f(x)=x^3 -3x^2 -5x +39

Answer 1

#1 There must be a typo here. Not factorable

#2 (x^2-25)(x^2+4)
now it should be easy

#3 a little tinkering shows that you have
(x+3)(x^2-6x+13)
again, complex roots.