Answer:
(-1, 0) and (0, 1)
Explanation:
There is one sign change, so one positive real root. f(0) = 11 and f(1) = -11, so the positive real root is in the interval (0, 1).
When odd term signs are negated, the signs become (- + - - +), so there are 3 sign changes. This means there is 1 or 3 negative real roots. f(-1) = -31, so there is a negative real root in the interval (-1, 0).
When we do synthetic division by x+1, we get alternating signs on the bottom line, indicating -1 is a lower bound on real roots.
Real roots are located between -1 and 0, and between 0 and +1.
_____
The graph of the function confirms this answer.