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Re: How to get Mathematica to actually *add* fractions?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg40559] Re: How to get Mathematica to actually *add* fractions?
  • From: adam.smith at hillsdale.edu (Adam Smith)
  • Date: Thu, 10 Apr 2003 03:37:33 -0400 (EDT)
  • References: <b70ck5$8al$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Use the command Together[]

thing = (2/(3x)) + (6/x) + (x/(x + 3))

Out[1]=
20/(3*x) + x/(3 + x)

In[2]:=
Together[thing]

Out[2]=
(60 + 20*x + 3*x^2)/(3*x*(3 + x))

Together can be a powerful tool when trying to obtain a specific form
of the result.  Just be aware that it is sometimes very time consuming
(if not nearly impossible) to get Mathematica to return a final form
that exactly matches some desired form (say that is quoted in a text).

Adam Smith

a_cjones at hotmail.com (cdj) wrote in message news:<b70ck5$8al$1 at smc.vnet.net>...
> Hi,
> 
> Like the subject says, but take for example:
> 
> (2/(3x)) + (6/x) + (x/(x + 3))
> 
> Sending to the kernel simply gives:
> 
> 20/3x + x/(3+x)
> 
> What I wanted/hoped for was the common-denominator version:
> 
> (3x^2 + 20x + 60)/(3x(x+3))
> 
> Is there any way to get Mathematica to give the one-denominator
> version of sums of fractions?
> 
> thanks,
> 
> cdj


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