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multiple of sum of fraction by common denominator keeps fractions in result

• To: mathgroup at smc.vnet.net
• Subject: [mg41585] multiple of sum of fraction by common denominator keeps fractions in result
• From: Friedrich Laher <mathefritz at schmieder-laher.de>
• Date: Wed, 28 May 2003 04:57:20 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

In[8]:=
\!\(\(1 - x\)\/\(5*\((1 - 2*x)\)\) - \(2 + x\)\/8 - 4 + \(2*x - 
19\)\/80\ x\)

Out[8]=
\!\(\(-4\) + 1\/8\ \((\(-2\) - x)\) + \(1 - x\)\/\(5\ \((1 - 2\ x)\)\) +
     1\/80\ x\ \((\(-19\) + 2\ x)\)\)

In[17]:=
Together[In[8]]

Out[17]=
\!\(\(324 - 635\ x - 60\ x\^2 + 4\ x\^3\)\/\(80\ \((\(-1\) + 2\ x)\)\)\)

In[18]:=
%*80*(-1+2x)

Out[18]=
\!\(324 - 635\ x - 60\ x\^2 + 4\ x\^3\)

In[19]:=
\!\(Expand[\((\(1 - x\)\/\(5*\((1 - 2*x)\)\) - \(2 + x\)\/8 -
           4 + \(2*x - 19\)\/80\ x)\)*80*\((1 - 2*x)\)]\)

Out[19]=
\!\(\(-340\) + 16\/\(1 - 2\ x\) + 651\ x - \(48\ x\)\/\(1 - 2\ x\) +
     60\ x\^2 + \(32\ x\^2\)\/\(1 - 2\ x\) - 4\ x\^3\)

In[20]:=
FullSimplify[Out[19]]

Out[20]=
-324+x (635-4 (-15+x) x)

In[21]:=
Expand[%]

Out[21]=
\!\(\(-324\) + 635\ x + 60\ x\^2 - 4\ x\^3\)

of what use could Out[1] be, why not directly Out[21] ?

• Follow-Ups:
  • Re: multiple of sum of fraction by common denominator keeps fractions in result
    • From: Daniel Lichtblau <danl@wolfram.com>