Stefano Ferri a ?crit :
> I had a look at your first problem, and it is linear in y.
No, it is not linear but cubic ; for instance
(%i70) coeff(expand(det1),y,3);
(%o70) x3^3-9*x2*x3^2+9*x1*x3^2-3*x0*x3^2+27*x2^2*x3-54*x1*x2*x3+18*x0*x2*x3
+27*x1^2*x3-18*x0*x1*x3+3*x0^2*x3-27*x2^3+81*x1*x2^2-27*x0*x2^2
-81*x1^2*x2+54*x0*x1*x2-9*x0^2*x2+27*x1^3-27*x0*x1^2+9*x0^2*x1-x0^3
and linsolve is dangerous since it doesn't check for linearity (and its
documentation says
"The expressions must each be polynomials in the variables and may be
equations. ", I don't understand why the word polynomial is used here).
For instance :
(%i1) linsolve(y^3+y+1,y);
(%o1) [y = - 1]
looks like a bug.
Eric Reyssat
> Instead of solve,
> try linsolve. It solves your problem in less than a second.
> But look how complicated is the solution, and simplifier cannot help you here.