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Rolle's Theorem Practice Problems

Check that f is continuous on [a, b], differentiable on (a, b) and that f(a) = f(b). Then solve f′(c) = 0 and keep only the values strictly between a and b.

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Rolle’s Theorem Practice Problems

These problems follow the Rolle’s theorem lesson. Most ask for the value of ; the last one uses the theorem to count the roots of an equation.

The method

  1. Check that is continuous on and differentiable on .
  2. Check that .
  3. Solve .
  4. Keep only the solutions strictly between and .

Common mistakes to watch for

  • Keeping an endpoint as a value of .
  • Missing a value when has several solutions inside the interval.
  • Using the theorem without checking the conditions, such as on a function with a corner.

Frequently Asked Questions

How should I type my answer?+

List every value of c separated by commas, in any order. You can type pi and sqrt( ), for example pi/2 or 2/sqrt(3).

Can c be one of the endpoints?+

No. Rolle's theorem places c strictly between a and b, so discard any solution of f′(c) = 0 that equals a or b.

More practice problems