Dear Konrad, I presume that the system can be written as follows, where h0, d0, ga0, kga and kd are given: err1 = h + hd + hga - h0; err2 = d + hd - d0; err3 = ga + hga - ga0; err4 = hga - kga*h*ga; err5 = hd - kd*h*d; All error terms should be zero. Do you need (a) the symbolic solution or (b) is a numeric solution fine? I do not have any experience with yacas or caracas. But see below. ### Case (a) I did write a (very rudimentary) symbolic solver for systems of polynomial equations in pure R. It should be able to solve this one. Please let me know if this is of interest and I will provide further details. ### Case (b) Again, it should be possible to solve, see some examples: https://github.com/discoleo/R/blob/master/Math/Systems.NLE.Tutorial.md https://github.com/discoleo/R/blob/master/Math/Systems.Lambert.R I did solve much more complex ones, for a monster see: https://github.com/discoleo/R/blob/master/Math/Poly.System.S5.Ht.Formulas.Derivation.HS0.R [and the remaining Poly.System.S5.Ht... scripts] I presume that only the real roots are required (it's possible to solve systems with complex roots as well). I can provide further details as well. Sincerely, Leonard [[alternative HTML version deleted]]