On Fri, Jun 15, 2007 at 07:31:24PM -0700, Richard Fateman wrote:
> ratsubst(q,x/D^2,a);
> factor(%);
> ratsubst(x/D^2,q,%);
>
> Does it. Gives
> -(x/D-1)*(x/D+1)/(3*x/D+1)^4
I get the right result when I do:
ratsubst(q,x/D,a);
factor(%);
subst(q=x/D,%);
What made you try the substitution of q=x/D^2 rather than x/D ?? This
substitution works in the ratsubst above as well, but is less
intuitive since the original question was to get the result in terms
of x/D.
I knew I would learn something useful from this question.
--
Daniel Lakeland
dlakelan at street-artists.org
http://www.street-artists.org/~dlakelan