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Re: How do I pick out the expression under a radical?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg36268] Re: How do I pick out the expression under a radical?
  • From: asb4 at psu.edu (Steve Beach)
  • Date: Thu, 29 Aug 2002 01:37:51 -0400 (EDT)
  • References: <akf64b$bgc$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Thank you all for your help.  

I had looked at using "Cases", but had gotten tripped up by
forgettting to use Infinity to tell it to look at all subexpressions. 
The tip from Bob Hanlon about how to use Algebra`InequalitySolve`
package helped too.


asb4 at psu.edu (Steve Beach) wrote in message news:<akf64b$bgc$1 at smc.vnet.net>...
> I'm a poor physicist trying to figure out how to sort out the
> "physical" from the "non-physical" solutions to a problem.  To do
> that, I need to be able to look at an expression and pick out a
> subexpression, the part under the radical.
> 
> For example, say I've got the expression 
> 
> a b x^2 + 5 x^3 + 5 Sqrt[4 - x^2]
> 
> I'd like to pick out "4 - x^2", which would then tell me that x is
> between +/- 2.  I know there has got to be an easy way to do it, but I
> can't find it.  Any help would be appreciated.
> 
> Thanks,
> 
> Steve Beach
> asb4 at psu.edu
> http://www.thebeachfamily.org


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