Handling expressions. Could any one find a more direct way?

*To*: mathgroup at smc.vnet.net*Subject*: [mg39911] Handling expressions. Could any one find a more direct way?*From*: guillerm at aida.usal.es (Guillermo Sanchez)*Date*: Tue, 11 Mar 2003 02:38:15 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

(*A need to obtain {k10, k21, k12, k13, k31} knowing that A = b where*) A = 0.1/(0.1 + s) + 0.2/(1 + s) + 0.7/(5 + s); b = (k21*k31 + k21*s + k31*s + s^2)/(k10*k21*k31 + k10*k21*s + k13*k21*s + k10*k31*s + k12*k31*s + k21*k31*s + k10*s^2 + k12*s^2 + k13*s^2 + k21*s^2 + k31*s^2 + s^3); (*Here is my procedure*) A1 = Together[ExpandAll[Factor[A]]] n1 = Numerator[A1] d1 = Denominator[A1] n2 = Collect[Numerator[b], s] d2 = Collect[Denominator[b], s] (*Now, handing the solution for previous output -they are been eliminated in this mail- I can obtain {k10, k21, k12, k13, k31}*) Solve[{k21*k31== 0.67, 2.39 == k21 + k31, k10*k21*k31 == 0.5, k10*k21 + k13*k21 + k10*k31 + k12*k31 + k21*k31 == 5.6, k10 + k12 + k13 + k21 + k31 == 6.1}, {k10, k21, k12, k13, k31}] (* Could any one find a more direct way?*) Guillermo Sanchez

**Follow-Ups**:**Re: Handling expressions. Could any one find a more direct way?***From:*Daniel Lichtblau <danl@wolfram.com>