RE: Simplify

• To: mathgroup at smc.vnet.net
• Subject: [mg32663] RE: [mg32654] Simplify
• From: "Florian Jaccard" <jaccardf at eicn.ch>
• Date: Mon, 4 Feb 2002 03:23:27 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```Hello !

Your solution is ok only if a end b are positive real numbers !

Don't forget that (a*b)^n is not a^n * b^n if n is rational and a and b not
real positive !

So if you write :

PowerExpand[Simplify[(a^(1/3) - b^(1/3)) * ((a^(2/3) + (a*b)^(1/3) +
b^(2/3))/(a-b))^(1/3),{a>0,b>0}]]

You will get what you want !

Meilleures salutations

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

-----Message d'origine-----
De : Stich Sebastian [mailto:seb_stich at gmx.ch]
Envoyé : ven., 1. février 2002 22:11
À : mathgroup at smc.vnet.net
Objet : [mg32654] Simplify

Hello

How can I simplify the following term?

(a^(1/3) - b^(1/3)) * ((a^(2/3) + (ab)^(1/3) + b^(2/3))/(a-b))^(1/3)

If I use the commands "Simplify", "FullSimplify", "Expand" or "PowerExpand"
mathematica doesn't find the solution.
The solution is (a^(1/3)-b^(1/3))^(2/3)
If it's possible to find the solution in mathematica could mathematica show
me the way this solution?