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Re: Integral problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg27905] Re: Integral problem
  • From: "Paul Lutus" <nospam at nosite.com>
  • Date: Fri, 23 Mar 2001 04:31:27 -0500 (EST)
  • References: <99cigc$8jq@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

"Jose Lasso" <jml at accessinter.net> wrote in message
news:99cigc$8jq at smc.vnet.net...
> Hello,
>
> Well in my calculus class, I need to integrate the following expression:
> (x^3/(x^4+x^2+1))dx, I solve the integral with Mathematica, but a few
> classmates got a different answer using other symbolic algebra
> system, the answers are totally different, the answer that my
> classmates got is:
> 1/4 Ln(x^4+x^2+1)-(Sqrt(3)/6) ArcTg((2x^2+1)/Sqrt(3)) is this the
> correct answer??

First, we cannot compare your result with theirs because you didn't give us
yours. The outcomes depend to a great extent on what options you gave to
Mathematica.

Here is one solution that makes no assumptions about the range of numerical
values x can have:

http://www.arachnoid.com/images/integral3.gif

This result was computed with this entry:

Integrate[x^3/(x^4+x^2+1),x]//FullSimplify//TraditionalForm

Why not say what you got for the integral, and how you got it?

--
Paul Lutus
www.arachnoid.com





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