Understanding Continuous Functions: Examining f'(7) Undefined

Click For Summary
SUMMARY

The discussion centers on the continuity of a function f at x = 7 when f'(7) is undefined. It is established that the correct conclusion is option C: there is not enough information to determine whether f is continuous at x = 7. The example function f(x) = |x - 7| illustrates a case where the derivative does not exist at x = 7, yet the function remains continuous. Conversely, f(x) = 1/(x - 7) serves as an example of a function that is neither continuous nor differentiable at x = 7.

PREREQUISITES
  • Understanding of calculus concepts, specifically derivatives and continuity.
  • Familiarity with piecewise functions and their properties.
  • Knowledge of limits and their role in determining continuity.
  • Ability to analyze functions for differentiability and continuity.
NEXT STEPS
  • Study the properties of piecewise functions and their continuity.
  • Learn about the implications of the Mean Value Theorem on differentiability.
  • Explore the concept of limits and how they relate to continuity in calculus.
  • Investigate examples of functions that are continuous but not differentiable, such as f(x) = |x|.
USEFUL FOR

Students and educators in calculus, mathematicians analyzing function behavior, and anyone interested in the nuances of continuity and differentiability in mathematical functions.

bearn
Messages
11
Reaction score
0
Suppose f is a function such that f'(7) is undefined. Which of the following statements is always true? (Give evidences that supports your answer, then explain how those evidences supports your answer)

a. f must be continuous at x = 7.
b. f is definitely not continuous at x = 7.
c. There is not enough information to determine whether or not f is continuous at x = 7.
 
Physics news on Phys.org
Can you think of a function f(x) where the derivative does not exist at x = 7 but is continuous there?

-Dan
 
topsquark said:
Can you think of a function f(x) where the derivative does not exist at x = 7 but is continuous there?

-Dan
No,
 
Last edited:
How about f(x) = |x - 7|?

-Dan
 
Oh, so the answer is a. f must be continuous at x=7?​
 
bearn said:
Oh, so the answer is a. f must be continuous at x=7?​
Can you think of a function f(x) that has no derivative at x = 7 and is not continuous there?

-Dan
 
I don't think there is
 
bearn said:
I don't think there is
What about [math]f(x) = \dfrac{1}{x - 7}[/math]?

-Dan
 
topsquark said:
What about [math]f(x) = \dfrac{1}{x - 7}[/math]?

-Dan
The answer should be C. then
 
  • #10
bearn said:
The answer should be C. then
Yes.

-Dan
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 6 ·
Replies
6
Views
3K
Replies
1
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 8 ·
Replies
8
Views
5K
Replies
2
Views
1K
  • · Replies 1 ·
Replies
1
Views
4K
Replies
7
Views
1K