eq:''diff(x + y =a, x);solve([eq],[dy/dx]);

Maybe you want something like this

(%i1) algebraic : true;
(%o1) true
(%i2) depends(y,x);
(%o2) [y(x)]
(%i3) diff(x^(1/2) + y^(1/2) = a^(1/2), x);
(%o3) 'diff(y,x,1)/(2*sqrt(y))+1/(2*sqrt(x))=0
(%i4) solve(%,diff(y,x));
(%o4) ['diff(y,x,1)=-sqrt(y)/sqrt(x)]
(%i5) %*2*sqrt(y);
(%o5) [2*sqrt(y)*('diff(y,x,1))=-(2*y)/sqrt(x)]
(%i6) rat(%);
(%o6) [2*sqrt(y)*('diff(y,x,1))=-(2*sqrt(x)*y)/x]


Barton

-----maxima-admin@math.utexas.edu wrote: -----

>To: maxima 
>From: Jorge Barros de Abreu
>
>Sent by: maxima-admin@math.utexas.edu
>Date: 04/24/2005 12:35PM
>Subject: eq:''diff(x + y =a,
>x);solve([eq],[dy/dx]);
>
>Changing the words:
>
>How I make the following situation?
>
>(%i2) depends(y,x);
>(%i3) diff(x^(1/2) + y^(1/2) = a^(1/2), x);
>(%i4) %-(1/(2*sqrt(x)));
>(%i5) %*2*sqrt(y);
>
>I need for (%o5) output with no square root in
>denominator an without (%i4)
>and (%i5) manual input.
>