From: nma@12000.org   
      
   On 10/4/2017 11:21 AM, clicliclic@freenet.de wrote:   
      
   > I believe that:   
   >   
   >    SQRT(x^2/(1 + SQRT(x^2 - 1))^2)*(1 + SQRT(x^2 - 1))/x = x/SQRT(x^2)   
   >   
   > FriCAS will probably squeal, but can Mathematica or Maple validate or   
   > invalidate this simplification?   
   >   
   > Martin.   
   >   
      
   fyi;   
      
   Mathematica says, for real x, the above is valid only for x<=1 || x>=1   
      
   In[1]:= expr1 = Sqrt[x^2/(1 + Sqrt[x^2 - 1])^2]*((1 + Sqrt[x^2 - 1])/x);   
   In[2]:= expr2 = x/Sqrt[x^2];   
   In[5]:= Reduce[expr1 - expr2 == 0, x, Reals]   
      
   Out[5]= x <= -1 || x >= 1   
      
   --Nasser   
      
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