[ Diff(x[1], t) = (1*k[5]*k[1]*ln(k[2]/x[1])*x[1] + (-1)*k[5]*x[1]*x[3]/(x[1] + x[2]))/k[5],
  Diff(x[2], t) = (1*k[5]*x[1]*x[3]/(x[1] + x[2]) + (-1)*k[5]*k[3]*x[2])/k[5],
  Diff(x[3], t) = (1*k[5]*k[3]*x[2] + (-1)*k[5]*k[4]*x[3])/k[5] ]