Answer:
Step-by-step explanation:
The constant tells us f(0) = 11.
The sum of coefficients tells us f(1) = -11.
Changing the signs of odd-degree terms and summing coefficients again tells us f(-1) = -31.
There will be real roots between values of x where there is a sign change in f(x), so ...
The x^4 term will dominate for x-values beyond -1 or 1, so these are the only intervals in which there will be real roots.