To find the zeroes you make the function equal to zero and then solve.
[tex]0=x^3-2x^2-3x[/tex]
Then factor out the x to get a quadratic inside the parentheses.
[tex]0=x(x^2-2x-3)[/tex]
Factor the inside quadratic formula.
[tex]x(x^2-2x-3)=x((x-3)(x+1))[/tex]
Lastly, use the zero product property to solve.
[tex]x*(x-3)*(x+1)=0 [/tex]
[tex]x=0,x=3,x=-1[/tex]