Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Re: Calculating derivate in Mathematica 9 giving wrong result

• To: mathgroup at smc.vnet.net
• Subject: [mg131414] Re: Calculating derivate in Mathematica 9 giving wrong result
• From: "Dave Snead" <dsnead6 at charter.net>
• Date: Wed, 3 Jul 2013 22:00:21 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
• Delivered-to: mathgroup-outx@smc.vnet.net
• Delivered-to: mathgroup-newsendx@smc.vnet.net
• References: <20130703090146.A8EAD6AD9@smc.vnet.net>

James,

Both results are correct.
The functions you are differentiating are different.

Cheers,
Dave Snead

-----Original Message----- 
From: James
Sent: Wednesday, July 03, 2013 2:01 AM
To: mathgroup at smc.vnet.net
Subject: [mg131414] Calculating derivate in Mathematica 9 giving wrong 
result

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.

• References:
  • Calculating derivate in Mathematica 9 giving wrong result
    • From: James <jhlawley@gmail.com>