newbie question, real positive solutions of an equation

> Thanks, this already eliminates complex roots. How can I select only the 
> positive roots?

I'm not sure there is a global variable controling this, and assume(x>0)
doesn't work here.

Try this work-around:

pos_roots(res):=
 sublist(res, lambda([z],member(sign(rhs(z[1])),['pos,'pz])));
algsys([x^2+2*x-3],[x]);
pos_roots(%);


If you want strictly positive roots, remove 'pz in the list above. See ?
sign for more details.

Mario
-- 
Mario Rodriguez Riotorto
www.biomates.net