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MathGroup Archive 2007

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  • To: mathgroup at smc.vnet.net
  • Subject: [mg77935] question
  • From: dimitris <dimmechan at yahoo.com>
  • Date: Wed, 20 Jun 2007 05:28:38 -0400 (EDT)

Hi.

Say

o=(16-x^2)^(1/2)-(4-x)^(1/2)*(4+x)^(1/2);

In another CAS one must use assumptions
in order to simplify

>o:=sqrt(16-x^2)-sqrt(4-x)*sqrt(4+x);
> combine(u) assuming x>-4,x<4 ;
> simplify(%);


                          2 1/2          1/2        1/2
              o := (16 - x )    - (4 - x)    (4 + x)

                        2 1/2                    1/2
                 (16 - x )    - ((4 - x) (4 + x))


                                  0


In Mathematica one simply gets

In[10]:=
Simplify[o]

Out[10]=
0


I would like to hear your comments on this issue.


Dimitris



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