From: Albert_Rich@msn.com   
      
   On Monday, January 11, 2021 at 1:33:07 PM UTC-10, Nasser M. Abbasi wrote:   
   > 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   
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