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Re: simplifying rational expressions

• To: mathgroup at smc.vnet.net
• Subject: [mg61111] Re: simplifying rational expressions
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Tue, 11 Oct 2005 03:20:04 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <did2q0$qde$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

krily wrote:
> If someone could be so kind as to show me how to simplify the following:
> 
> [(t^4-1)(t^2-9)(t-9)^2]/[(t^4-81)(t^2+1)(t+1)^2]
> 
First, use the correct syntax to group expressions: right and left 
parentheses rather than right and left squared brackets.

In[1]:=
expr = ((t^4 - 1)*(t^2 - 9)*(t - 9)^2)/((t^4 - 81)*(t^2 + 1)*(t + 1)^2)

Out[1]=
((-9 + t)^2*(-9 + t^2)*(-1 + t^4))/((1 + t)^2*(1 + t^2)*(-81 + t^4))

Then, *Cancel* could be a good start to simplify rational expression

In[2]:=
Cancel[expr]

Out[2]=
((-9 + t)^2*(-1 + t))/((1 + t)*(9 + t^2))

Hope this helps,
/J.M.