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Re: Calculating derivate in Mathematica 9 giving wrong result

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  • Subject: [mg131423] Re: Calculating derivate in Mathematica 9 giving wrong result
  • From: "Dr. Wolfgang Hintze" <weh at snafu.de>
  • Date: Wed, 3 Jul 2013 22:03:22 -0400 (EDT)
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Am Mittwoch, 3. Juli 2013 10:52:25 UTC+2 schrieb James:
> In[5]:= D[(x^2 - 2)/(x^3 + 6), x]
> 
> 
> 
> Out[5]= -((3 x^2 (-2 + x^2))/(6 + x^3)^2) + (2 x)/(6 + x^3)
> 
> 
> 
> That is from Mathematica 9.
> 
> 
> 
> The wolfram alpha site and my textbook give this answer:
> 
> 
> 
> d/dx((x^2+x-2)/(x^3+6)) = (-x^4-2 x^3+6 x^2+12x+6)/(x^3+6)^2
> 
> 
> 
> Please tell me what I am doing wrong.

Both results are correct. 

But the expressions you try to derive are not identical (in the second one there appears an extra "x").

Regards,
Wolfgang



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