Extreme value theorem question?

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SUMMARY

The discussion centers on the application of the Extreme Value Theorem (EVT) to the function g(x) = 1/(x-2) defined on the interval [3, ∞). Participants clarify that the EVT states a continuous function must attain a maximum or minimum on a closed interval. Since [3, ∞) is not a closed interval, g(x) does not contradict the EVT as it lacks a minimum value on this interval. The correct interpretation emphasizes that the EVT applies strictly to closed intervals, such as [3, a], where a is any number greater than 3.

PREREQUISITES
  • Understanding of the Extreme Value Theorem (EVT)
  • Knowledge of continuous functions
  • Familiarity with closed and open intervals
  • Basic calculus concepts related to limits and function behavior
NEXT STEPS
  • Review the definition and implications of the Extreme Value Theorem
  • Study the characteristics of continuous functions on closed intervals
  • Explore examples of functions defined on open intervals and their properties
  • Investigate the concept of limits and behavior of functions as they approach infinity
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Students studying calculus, mathematics educators, and anyone seeking to understand the implications of the Extreme Value Theorem in relation to continuous functions and interval definitions.

indigo1
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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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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?
 
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.
 

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