Finding Whether Improper Integrals Converge

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SUMMARY

The discussion centers on evaluating the improper integral ∫10(xln(x))dx, with the conclusion that it converges to -1/4. Participants clarify the limits of the function as x approaches 1 from the left and 0 from the right, confirming that lim(xlnx) as x approaches 0+ equals ∞. The use of L'Hôpital's Rule is suggested as a method to resolve the integral, leading to the correct evaluation from 0 to 1.

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  • Understanding of improper integrals
  • Familiarity with L'Hôpital's Rule
  • Knowledge of logarithmic functions
  • Basic calculus concepts, including limits and integration
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  • Study the application of L'Hôpital's Rule in evaluating limits
  • Explore techniques for solving improper integrals
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Students and educators in calculus, mathematicians interested in integral calculus, and anyone seeking to deepen their understanding of improper integrals and convergence.

rocapp
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Hi all,

I'm having trouble with finding an improper integral.

The problem is ∫10(xln(x))dx

My book says the answer is -1/4, but I do not understand how this is the case.

lim(xlnx) as x approaches 1- = 0

lim(xlnx) as x approaches 0+ = ∞

So how does this value converge at -1/4?

Thanks in advance!
 
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rocapp said:
lim(xlnx) as x approaches 0+ = ∞

What makes you say that? Did you try Lhopital?
 
Ah. I see that. So now I just find the integral and from zero to one, correct?
 

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