Re: Dividing top and bottom

• To: mathgroup at smc.vnet.net
• Subject: [mg15641] Re: [mg15591] Dividing top and bottom
• From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
• Date: Sat, 30 Jan 1999 04:28:39 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```On Thu, Jan 28, 1999, Nicolas B.E. Sawyer <nbes at eee.nott.ac.uk> wrote:

>How can I divide the denominator and numerator of an expression by a
>chosen variable and stop the result from simplifying. For example, how
>do I  divide the top and bottom of b/(b-a) by b to give 1/(1-a/b).
>
>Thanks
>
>--
>Nicolas B.E. Sawyer
>
>
>Department of Electrical and Electronic Engineering, University of
>Nottingham,
>University Park,
>Nottingham,
>NG7 2RD.
>
>Tel: +44 115 9515151 ext 12028
>Fax: +44 115 9515616
>
>E-mail: nbes at eee.nottingham.ac.uk

I can think of several way to do this. Perhaps the simplest way is to
define a function

In[16]:=
transform[x_,f_]:=Expand[f[Numerator[x]]]/Expand[f[Denominator[x]]]

Now

In[17]:=
transform[b/(b-a),#/b&]
Out[17]=
1
-----
a
1 - -
b

Another very simple way is to do this "by hand". I do not actually mean
"without using Mathematica" (though that is indeed the simplest way to
solve this problem) but simply by entering /b into the top and bottom
and than using the Simplify button on the Algebraic Manipulation
pallete to simplify the numerator and the denominator separately.

Andrzej Kozlowski
Toyama International University
JAPAN
http://sigma.tuins.ac.jp/
http://eri2.tuins.ac.jp/

```

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