Answer:
{-2/3, 2/3, 3}
Explanation:
The equation can be factored by grouping.
f(x) = (9x^3 -27x^2) +(-4x +12)
f(x) = 9x^2(x -3) -4(x -3)
f(x) = (9x^2 -4)(x -3)
We recognize the first factor as the difference of squares, so know it can be further factored to give ...
f(x) = (3x -2)(3x +2)(x -3)
The zeros are the values of x that make these factors be zero:
3x -2 = 0 ⇒ x = 2/3
3x +2 = 0 ⇒ x = -2/3
x -3 = 0 ⇒ x = 3
The zeros of the polynomial are x = -2/3, 2/3, 3.