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Re: Radicals simplify

  • To: mathgroup at smc.vnet.net
  • Subject: [mg106390] Re: Radicals simplify
  • From: Peter Breitfeld <phbrf at t-online.de>
  • Date: Mon, 11 Jan 2010 05:31:21 -0500 (EST)
  • References: <hic37h$5ef$1@smc.vnet.net>

"francix" wrote:

> Hi,
> I am using Matematica 7 and need some help with Radicals.
>
> If I do
> Simplify[(x^4 y^3)^(1/4), x >= 0] I correctly have
>
> x (y^3)^(1/4)
>
> But If I do
>
> Simplify[(x^6 y^3)^(1/4), x >= 0] I get
>
> (x^6 y^3)^(1/4) and not the correct answer  x(x^2 y^3)^(1/4)
>
> Thanks in advanced.

expr=(x^6 y^3)^(1/4);

You may use Refine instead of Simplify:

Refine[expr,x>=0]
Out= x^(3/2) (y^3)^(1/4)

Or, because you know that all variables are non negative, you may use
PowerExpand:

PowerExpand[expr]
Out= x^(3/2) y^(3/4)

But I think you can't get the result  x(x^2 y^3)^(1/4)

-- 
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de


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