What are the zeros of the polynomial function: f(x) = x^3 – 9x^2 + 20x ?

0, 5, 4. Here is how you get it. x^3-9x^2+20x = (x) (x^2 - 9x +20) = (x) (x -5) (x - 4). The roots then are 0, 5, 4.