Please help with Rationals

Hi, I have this function, g(x)= (x^3-x)/(x^3-4x).

Now I need help with the following...

- How to find the **zeros** for f?

- How to find f(-x)?

- How to find point of discontinuity?

And also, would finding the asymptotes, slant asymptote, and point of discontinuity be easier if I simplify this rational first?:

(2x^3-3x^2-12x+20)/(x^2-5x+6)

I can simplify the denominator as (x+1)(x-6) but that's it...

Is the first step to simplifying the numerator... Factoring out x?

I'd appreciate any help, thanks so much!