Proving a Function Is Riemann Integrable

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SUMMARY

The discussion centers on proving the Riemann integrability of a specific function as outlined in a homework problem from a Math 4603 course. The key equation under scrutiny involves the summation of products of differences and squares of function values, specifically $$= \sum_{i=0}^{n-1} (x_{i+1} - x_i)(x^2_{i+1} + x_{i+1}x_i + x_i^2) (x_{i+1} - x_i)$$. The user is attempting to show that this expression is less than a certain threshold, represented by $$< \delta 3 \sum_{i=0}^{n-1} (x_{i+1} - x_i)$$. The critical insight provided is that the inequalities ##x_i \le 1## and ##(x_{i+1}-x_i) < \delta## for all ##i## should be utilized to simplify the proof.

PREREQUISITES
  • Understanding of Riemann integrability concepts
  • Familiarity with summation notation and limits
  • Knowledge of inequalities in calculus
  • Proficiency in manipulating polynomial expressions
NEXT STEPS
  • Study the properties of Riemann integrable functions
  • Learn about the application of inequalities in calculus proofs
  • Explore the concept of partitions in Riemann integration
  • Review polynomial approximation techniques in analysis
USEFUL FOR

Students in advanced calculus or real analysis courses, particularly those tackling Riemann integration problems, as well as educators seeking to clarify integrability concepts.

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Homework Statement


Here is a link to the problem which I am currently working on:

http://math.umn.edu/~jara0025/Math4603/Math4603H9Answers.pdf

Homework Equations

The Attempt at a Solution


[/B]
The specific problem I am working on is found on page 3, and is the first problem on that page. The step I am having trouble with is

$$= \sum_{i=0}^{n-1} (x_{i+1} - x_i)(x^2_{i+1} + x_{i+1}x_i + x_i^2) (x_{i+1} - x_i)$$

$$ < \delta 3 \sum_{i=0}^{n-1} (x_{i+1} - x_i)$$

What is going on?
 
Last edited by a moderator:
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Bashyboy said:

Homework Statement


Here is a link to the problem which I am currently working on:

http://math.umn.edu/~jara0025/Math4603/Math4603H9Answers.pdf

Homework Equations

The Attempt at a Solution


[/B]
The specific problem I am working on is found on page 3, and is the first problem on that page. The step I am having trouble with is

$$= \sum_{i=0}^{n-1} (x_{i+1} - x_i)(x^2_{i+1} + x_{i+1}x_i + x_i^2) (x_{i+1} - x_i)$$

$$ < \delta 3 \sum_{i=0}^{n-1} (x_{i+1} - x_i)$$

What is going on?

The point is that ##x_i \le 1## and ##(x_{i+1}-x_i) \lt \delta## for all ##i##. Try using those inequalities.
 
Last edited by a moderator:

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