wxMaxima cannot reduce system to a polynomial in one variable [closed]
I'm attempting to use wxMaxima 11.04.0 to solve some non-linear equations symbolically, but I get the error "algsys: tried and failed to reduce system to a polynomial in one variable; give up.". Having solved these eqns by hand, I believe there is a solution. Since I am new to wxMaxima, I am probably using it incorrectly. Can someone suggest how I can get the solution I want?
Here is the wxMaxima transcript: (%i1) A14:d=sr/(DM); A11:\alpha \eta *(M(1-d)/\rho)^(1/3)D=r/F; (%o1) d=(rs)/(DM) (%o2) (alpha(1-d)^(1/3)etaD*M^(1/3))/rho^(1/3)=r/F [this is actually rendered with Greek letters]
(%i3) solve([%o1,%o2],[d,D]); algsys: tried and failed to reduce system to a polynomial in one variable; give up.
Substituting d from A14 into A15 yields a cubic in D. I would like to see that, and also the solution of that cubic. For values of the parameters s, r, etc that I will use, there will be only one real root, but of course 'solve' can't know that, as I have asked for a symbolic solution.
This is not a Maxima help list. They are usually quite responsive to even simple help requests, though, so I encourage you to go to http://www.math.utexas.edu/mailman/listinfo/maxima and sign up!
Incidentally, solve in more than one variable does use algsys and sometimes does fail. You may want to import the to_poly_solve package which tries some trickier things first.