Gracious! They were supposed togiveyou the Theorem in your book!

Rolle's Theoremstates that, if a function f(x) is continuous on a closed interval [a, b] and differentiable on the open interval (a, b), and if f(a) = f(b), then there exists some x = c within the interval (a, b) such that f'(c) = 0.

To "show" that the given function "satisfies the hypothesis" (the "is continuous", "is differentiable", and "is equal-valued" bits), you need to show or state that each of these "givens" or if-statements is true. Are polynomials continuous? (You should have a rule or assumption for this.) Are polynomials differentiable? (You should have a rule or assumption for this.) Does f(-1) equal f(1)? (For this, evaluate f(x) at x = -1 and at x = 1, and compare their values.)

Then, once that's done, you can apply the "then" part. What does Rolle's Theorem say that the value of f(c) will be, for some x = c?