4x^2 - x^3 - 4x

------------------- is > or = to 0

4x^2 - 1

i factored it to

x(x-2)(x-2)

------------- is > or = to 0

(2x-1)(2x+1)

i think

Solving Inequalities: An Overview

this is how to do it, but i can't figure out everything they're doing or how to apply it

thx