Can You Solve This Challenging Improper Integral?

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SUMMARY

The discussion focuses on solving the improper integral of the function 1/(sqrt[x]*(1+x)) from 0 to infinity. The integral is split into two parts: from 0 to 1 and from 1 to infinity. The integral from 1 to infinity converges to 0, while the integral from 0 to 1 diverges as it approaches infinity. The user suggests using the substitution u = √x to simplify the problem and apply comparison tests for convergence.

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  • Understanding of improper integrals and their convergence
  • Familiarity with integration techniques, specifically substitution
  • Knowledge of comparison tests for integrals
  • Basic proficiency in calculus, particularly with limits and functions approaching infinity
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  • Study the method of substitution in integrals, focusing on u-substitution
  • Learn about comparison tests for determining the convergence of improper integrals
  • Explore the properties of improper integrals, particularly those involving limits
  • Practice solving similar improper integrals to reinforce understanding
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Students studying calculus, particularly those focusing on improper integrals and convergence tests, as well as educators looking for examples to illustrate these concepts.

RoganSarine
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[Solved] Improper Integral Integration

Sorry, don't know how to use the latex stuff for integrals :P

Homework Statement



Integrate the following from 0 to infinity: 1/(sqrt[x]*(1+x))

Homework Equations



Integrate 0 to 1: 1/(sqrt[x]*(1+x))
Integrate from 1 to infinity: 1/(sqrt[x]*(1+x))

The Attempt at a Solution



Integrate from 1 to infinity: 1/(sqrt[x]*(1+x))
This is convergent because you can tell as it goes to infinity, it will approach 0.

So, I should (i think) be able to find the integral of this, but... I can't use improper fractions because that square root messes everything up (atleast, from my understanding how improper fractions work... When I try to break it up, the square root always ends up negative).

Integrate 0 to 1: 1/(sqrt[x]*(1+x))
This shoots off to infinity as the function approaches zero, so...

If b = 0
lim x -> b+ Integrate b to 1: 1/(sqrt[x]*(1+x))

If x gets really close to zero, I can assume
1/(sqrt[x]*(1+x)) ~ 1/(sqrt[x])

Therefore, by using comparison tests,

1/(sqrt[x]*(1+x)) \geq 1/(sqrt[x])

Since I know that (1/x^p) is convergent if p<1 for any bounds between 0-1.

Basically, I know the theory... I just got no idea how to solve the rest of it.
 
Last edited:
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Try the substitution u = √x
 

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