Math Problem Statement
Consider the following function. f(x) = 4 − x2/3 Find f(−8) and f(8).
f(−8)
f(8)
Find all values c in (−8, 8) such that
f '(c) = 0.
(Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)
c =
Based off of this information, what conclusions can be made about Rolle's Theorem?
This contradicts Rolle's Theorem, since f is differentiable, f(−8) = f(8), and f '(c) = 0 exists, but c is not in (−8, 8).
This does not contradict Rolle's Theorem, since f '(0) = 0, and 0 is in the interval (−8, 8).
This contradicts Rolle's Theorem, since f(−8) = f(8), there should exist a number c in (−8, 8) such that f '(c) = 0.
This does not contradict Rolle's Theorem, since f '(0) does not exist, and so f is not differentiable on (−8, 8).
Nothing can be concluded.
Solution
Let's solve this step-by-step.
Step 1: Evaluate and
The given function is:
Now, substitute and to find and .
For :
The cube root of is , and squaring gives . So,
For :
The cube root of is , and squaring gives . So,
Thus, and .
Step 2: Find
Now, we differentiate the function .
Using the power rule for differentiation:
So,
Step 3: Find such that
Set :
For this equation to hold, there is no value of that makes . This implies that there is no in the interval such that .
Therefore, the answer for is:
Step 4: Rolle's Theorem
Rolle's Theorem states that if a function is continuous on the closed interval , differentiable on the open interval , and , then there exists at least one such that .
In this case:
- , so the first condition is satisfied.
- However, the derivative involves , which is undefined at . This means the function is not differentiable at .
Thus, this does not contradict Rolle's Theorem, since the function is not differentiable on the entire interval .
The correct conclusion is:
Do you need more details on any part of this explanation?
Here are some related questions you could explore:
- How is the cube root of a negative number defined in general?
- What are the key conditions of Rolle's Theorem?
- What happens if a function is not differentiable at a single point in the interval?
- Can a function still be continuous even if it's not differentiable everywhere?
- How do we find critical points where the derivative doesn't exist?
Tip: Always check if the function is differentiable across the entire interval when applying Rolle's Theorem!
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Math Problem Analysis
Mathematical Concepts
Algebra
Differentiation
Rolle's Theorem
Formulas
f(x) = 4 − x^(2/3)
f'(x) = -2/3 * x^(-1/3)
Theorems
Rolle's Theorem
Suitable Grade Level
Grades 11-12 or Calculus 1
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