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Re: how do you prevent numerator expansion when using 'Together'?

• To: mathgroup at smc.vnet.net
• Subject: [mg122279] Re: how do you prevent numerator expansion when using 'Together'?
• From: dimitris <dimmechan at yahoo.com>
• Date: Sun, 23 Oct 2011 06:24:12 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <j7u4u8$t7b$1@smc.vnet.net>

On Oct 22, 1:12 pm, Dushan Mitrovich <dush... at nnips.net> wrote:
> I'm using Mathematica 8.  When using 'Together' on an expression the numerator
> is always expanded, complicating the appearance of the final result:
>
>      In:  Together[ (a+b)/d + ((a+b)*(e+f))/(d*g) ]
>      Out: 1/(d*g) * (a*g + b*g + a*e + b*e + a*f + b*f)
>
> Instead, I'd much prefer the simpler form
>           1/(d*g) * (a+b)*(g+e+f)
>
> What do I need to do to get the latter form?  Thanks.
>
> - Dushan
>    [ reverse the middle word of address to reply ]

In version 5.2 you can use

In[11]:=
Simplify[Together[(a + b)/d + ((a + b)*(e + f))/(d*g)]]

Out[11]=
((a + b)*(e + f + g))/(d*g)

Dimitris