What Are Some Challenging Integrals for Calculus Enthusiasts?

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Discussion Overview

The discussion focuses on identifying challenging integrals suitable for calculus enthusiasts, particularly within the scope of Calculus I and II. Participants share various integrals they find difficult or interesting, aiming to enhance their practice beyond standard textbook problems.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant expresses a desire for tricky integrals beyond those found in standard textbooks, mentioning that they struggle to create their own challenging problems.
  • Another participant suggests using the forum's search function to find integrals, indicating that there may be a wealth of resources available.
  • A participant lists several specific integrals, including \int \sin(\ln x) + \cos(\ln x)dx and \int \frac{x^2}{x^2 +4x + 8} dx, noting that they have simple, clever solutions.
  • One integral, I_4 = \int_{0}^{\infty} \dfrac{x^{29}}{(5x^2+49)^{17}} \, dx, is highlighted as tricky but solvable with simple substitutions, with a specific solution provided.
  • Another participant shares an integral \int\frac{4x^5-1}{(x^5+x+1)^2}dx, stating it can be difficult until the solution is revealed, and recommends Apostol's calculus book for more challenging integrals.

Areas of Agreement / Disagreement

Participants generally agree on the interest in challenging integrals, but there is no consensus on specific integrals or methods, as different integrals are proposed without resolution on their relative difficulty.

Contextual Notes

Some integrals mentioned may depend on specific techniques or substitutions that are not detailed in the discussion, leaving the methods of solution open to interpretation.

Who May Find This Useful

Calculus students, educators, and enthusiasts looking for challenging integrals to practice or explore further.

QuarkCharmer
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I'm looking for some tricky/difficult integrals within the scope of calc I and II that I can play around with. Most of the integrals in my books (Stewart and Spivak) are fairly straight forward, and the only real practice I get is in "rigor". I can't really make up my own problems either, because I always come up with something unsolvable (without a CAS et al).

What are some good integrals??
 
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QuarkCharmer said:
What are some good integrals??

You may hit the SEARCH of this forum with 'integrals'.
 
https://www.physicsforums.com/showpost.php?p=3433157&postcount=272
[tex]\int \sin(\ln x) + \cos(\ln x)dx[/tex]
[tex]\int \frac{x^2}{x^2 +4x + 8} dx[/tex]
[tex]\int \frac{1}{\sqrt{5x-3}+\sqrt{5x+2}} dx[/tex]
[tex]\int \left( x^2 + 1\right) e^{x^2}dx[/tex]
[tex]\int \frac{1}{\sqrt[3]{x} + x} dx[/tex]
The integral below is tricky, BUT it can be solved using only simple substitutions.
Show that

[tex]I_4 \, = \, \int_{0}^{\infty} \dfrac{x^{29}}{(5x^2+49)^{17}} \, dx \,=\, \dfrac{14!}{2\cdot 49^2 \cdot 5^{15 }\cdot 16!}[/tex]

What I like about these integrals, is that most of them have simple, clever solutions.
 
Last edited:
Here's one which had me stumped for a while:

[tex]\int\frac{4x^5-1}{(x^5+x+1)^2}dx[/tex]

Once you see the solution of this one, you immediately get it. But without seeing the solution, it can be quite hard.

I'd suggest getting Apostol's calculus book. It is filled with hard integrals.
 

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