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MathGroup Archive 2002

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RE: FullSimplify doesn't simplify

  • To: mathgroup at smc.vnet.net
  • Subject: [mg32772] RE: [mg32762] FullSimplify doesn't simplify
  • From: "Florian Jaccard" <jaccardf at eicn.ch>
  • Date: Sat, 9 Feb 2002 05:11:43 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Hello Ken !

Yes, there are cases !

For exemple,  (-1)^(1/2)*(-1)^(1/2)=-1
but ((-1)(-1))^(1/2)=1

It is not a Mathematica problem, but Mathematics !

Remember : (a*b)^n=(a^n)*(b^n)  is always true only if a and b are real
positive numbers.

Indeed, Mathematica knows it :

In[1]:= Simplify[(a*b)^n==a^n*b^n,{a>0,b>0}]

Out[1]= True

Greetings

Florian Jaccard
EICN-HES
e-mail : jaccardf at eicn.ch


-----Message d'origine-----
De : Ken Morgan [mailto:kmorga51 at calvin.edu]
Envoyé : ven., 8. février 2002 09:50
À : mathgroup at smc.vnet.net
Objet : [mg32762] FullSimplify doesn't simplify


Does anyone know why Mathematica doesn't simplify the following to True?


In[1] := FullSimplify[(x y)^n == (x^n)(y^n)]

Out[1] := (x y)^n == (x^n)(y^n)

Are there cases where this is not true?


Thanks,
Ken Morgan
kmorga51 at calvin.edu





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