Trouble finding the derivative

  • Thread starter raul_l
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  • #1
raul_l
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Hi

I'm having trouble finding the derivative of this function.

[tex] y=x ln (x+\sqrt{1+x^2})-\sqrt{1+x^2} [/tex]

This is what I've tried so far, but I seem to be getting nowhere.
 

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Answers and Replies

  • #2
arildno
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Hi raul!
The nasty part of this is, of course the logarithm part, and possibly rearranging the expression you get afterwards.

For starters:
What is the derivative wrt. x of [itex]\sqrt{1+x^{2}}[/itex]?
 
  • #3
raul_l
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[tex] -\frac{x}{\sqrt{1+x^2}} [/tex] ?
 
  • #4
arildno
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Why the minus sign??
 
  • #5
raul_l
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Right, no minus sign there.. my bad.

However, now I get [tex] \ln(x+\sqrt{1+x^2}) [/tex]
Is this correct?
 

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