RootIntervals gives a list of isolating intervals for the real roots of any of the , together with a list of which polynomials actually have each successive root.
RootIntervals[poly] gives isolating intervals for real roots of a single polynomial.
The coefficients of poly must be integers or rationals.
An isolating interval for a root of a polynomial poly is an interval where the only root of poly contained in the interval is .
If a root is real, the isolating interval is an open real interval, or a point. If a root is not real, the isolating interval is an open rectangle, disjoint from the real axis.
Multiple roots give multiple entries in the second list generated by RootIntervals.