The function given is:

$f(x) = 4x^5 - 18x^4 - 6x^3 + 91x^2 - 60x + 9$

To find all the zeros of this polynomial, we will apply various algebraic techniques including factoring and using numerical methods if necessary.

Step 1: Factorization and Rational Root Theorem

We will first test for possible rational roots using the Rational Root Theorem. This theorem states that any rational solution $\frac{p}{q}$, where $p$ is a factor of the constant term and $q$ is a factor of the leading coefficient, could be a root of the polynomial.

Let's check for rational roots and factor the polynomial accordingly.