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Re: Forcing functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg51042] Re: Forcing functions
  • From: "David W. Cantrell" <DWCantrell at sigmaxi.org>
  • Date: Sat, 2 Oct 2004 03:18:40 -0400 (EDT)
  • Organization: NewsReader.Com Subscriber
  • References: <200302110942.EAA26084@smc.vnet.net> <b2d1cl$eaa$1@smc.vnet.net> <cjj7b4$bo4$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Barry Tesman <tesman at dickinson.edu> wrote:
> Can you "force" Mathematica to not use certain functions?  E.g., I
> want to give my students some problems to antidifferentiate.  One
> such problem is:
>
> Integrate[ x * Sqrt[x^2 + 2x +4], x]
>
> The answer uses arcsinh.  Can one force Mathematica to use natural
> log instead?

Perhaps what you want is

TrigToExp[Integrate[x*Sqrt[x^2 + 2*x + 4], x]]

(1/6)*(Sqrt[4 + 2*x + x^2]*(5 + x + 2*x^2)
        - 9*Log[(1 + x)/Sqrt[3] + Sqrt[1 + (1/3)*(1 + x)^2]])

David Cantrell


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