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Calculating derivate in Mathematica 9 giving wrong result

• To: mathgroup at smc.vnet.net
• Subject: [mg131406] Calculating derivate in Mathematica 9 giving wrong result
• From: James <jhlawley at gmail.com>
• Date: Wed, 3 Jul 2013 05:01:46 -0400 (EDT)
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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.

• Follow-Ups:
  • Re: Calculating derivate in Mathematica 9 giving wrong result
    • From: Bob Hanlon <hanlonr357@gmail.com>
  • Re: Calculating derivate in Mathematica 9 giving wrong
    • From: "Louis Talman" <talmanl@gmail.com>
  • Re: Calculating derivate in Mathematica 9 giving wrong result
    • From: "Dave Snead" <dsnead6@charter.net>