Hello, I was hoping someone could explain how to use the technique of Rolle's Sequence in order to determine the intervals in which the roots of a polynomial are contained. I know the technique involves taking the first and second derivative of the function and considering their signs, but beyond this I am unsure of how it works. Could someone demonstrate the technique on a polynomial like :

f(x)=x^3 +2x^2 -3x-1 ?

If any part of my question was unclear please let me know and I will be glad to specify. Thanks in advance!