Answer
$f(x)=x^3-3x^2-4x+12.$
Work Step by Step
If $c$ is a zero of a function with multiplicity $b$ then $(x-c)^b$ is a “factor” of the function.
We are given that the degree is $3$, and the zeros are $-2$, $2$ and $3$, hence
$f(x)=a(x+2)(x-2)(x-3)=a(x^3-3x^2-4x+12)$
When $a=1$ the function is
$f(x)=x^3-3x^2-4x+12$