Extreme value theorem question?

In summary, the given function g(x) = 1/x-2 is continuous and defined on the interval [3, infinity). However, it has no minimum value on this interval, which does not contradict the Extreme Value Theorem (EVT) as the interval is not a definite interval. According to the EVT, a continuous function will attain a max/min on a closed and bounded interval. [3, a] where a > 3 could achieve its minimum at x = a, making it a suitable interval for EVT.
  • #1
indigo1
3
0

Homework Statement



Given g(x) = 1/x-2 is continuous and defined on [3, infinity). g(x) has no minimum value on the interval [3, infinity ). Does this function contradict the EVT? Explain.



The Attempt at a Solution



was wondering what would be a better explanation for this one?

No, because the the extreme value theorems says that a continuous function defined on a DEFINITE interval will attain a max/min in the interval. [3, ∞) is not a definite interval. [3, a] where a is some number greater than 3 is and would achieve its minimum at x = a.

or

g has no minimum on this interval even though its continuous. It does not contradict how ever because the interval is not open.
 
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  • #2
I don't think the EVT says anything about DEFINITE intervals, nor does it says anything about open intervals. What kind of intervals does it talk about?
 
  • #3
indigo1 said:
No, because the the extreme value theorems says that a continuous function defined on a DEFINITE interval will attain a max/min in the interval. [3, ∞) is not a definite interval. [3, a] where a is some number greater than 3 is and would achieve its minimum at x = a.

The thought process behind this answer seems appropriate and correct. :smile:

Though, there is no 'definite interval'. You need to rephrase that word looking back at the definition of EVT.
 

1. What is the Extreme Value Theorem?

The Extreme Value Theorem states that a continuous function on a closed interval must have a maximum and minimum value.

2. What is the importance of the Extreme Value Theorem?

The Extreme Value Theorem is important because it allows us to determine the maximum and minimum values of a function on a given interval, which can be useful in optimization problems.

3. How is the Extreme Value Theorem different from the Mean Value Theorem?

The Mean Value Theorem states that for a differentiable function on an interval, there exists a point where the slope of the tangent line is equal to the average rate of change of the function. The Extreme Value Theorem deals with the maximum and minimum values of a function, while the Mean Value Theorem deals with the average rate of change.

4. Can the Extreme Value Theorem be applied to all functions?

No, the Extreme Value Theorem only applies to continuous functions on a closed interval. If a function is not continuous, or the interval is not closed, the theorem does not hold.

5. How is the Extreme Value Theorem used in real-world applications?

The Extreme Value Theorem can be used in real-world applications such as finding the optimal production level for a company or determining the maximum and minimum values of a stock price over a given time period.

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