Is log(log(1+1/r)) in L^N(B(0,1))?

  • Thread starter Palindrom
  • Start date
  • #1
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Homework Statement


Ok, so we're in R^N, and we're looking at the unit ball. I wanna prove that the function g(x)=log(log(1+1/r)) is in L^N of the unit ball, where r=|x|.
I also want to prove that its partial derivative are there, but like we say here, one cow at a time.:smile:


Homework Equations


None, really.


The Attempt at a Solution


Well, I don't remember if it's true, but maybe if xf(x) tends to zero when x tends to zero and f>0, then its integral is finite? I could then try and use it on |g|^N...
Any help would be immensly appreciated.
 

Answers and Replies

  • #2
StatusX
Homework Helper
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What does L^N of the unit ball in R^N mean? If it means Lp(B^N), where B^N is the unit ball in R^N, and Lp(X) is the space of complex valued functions on X whose magnitude to the pth power is integrable, p>=1, then:

Two steps:
1. show (log(x))^p<x for all p>=1, all x>N, some N depending on p.
2. show log(1+1/r) is integrable
 
Last edited:
  • #3
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Thanks, success!:smile:
 

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