From: nma@12000.org   
      
   Should CAS solve   
      
         sqrt(y)=x   
      
   for y by giving solution as y=x^2 without saying this is valid only for x>=0 ?   
      
   Only Maxima would ask the user if x was negative,positive or zero when   
   solving this equation.   
      
   Maple:   
   =======   
   eq:=sqrt(y)=x;   
   PDEtools:-Solve(eq,y);   
                y = x^2   
      
   Mathematica:   
   =============   
   eq = Sqrt[y] == x;   
   Solve[eq, y]   
                   {{y -> x^2}}   
      
   Maxima   
   =======   
   (%i1) solve(sqrt(y)=x,y)   
   Is x positive, negative or zero?   
       positive   
                                             2   
   (%o1)                              [y = x ]   
      
   Fricas   
   ========   
   solve(sqrt(y)=x,y)   
                  2   
       (4)  [y = x ]   
      
      
   At school, if I wrote in the exam that the solution of   
   sqrt(y)=x is y=x^2 without saying this is for x>=0, the   
   teacher will take one or more point off.   
      
   Why do then most CAS systems get away with it then? Is this just by convention   
   then?   
      
   --Nasser   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)