[ Diff(x[1], t) = (1*k[3]*k[1]/(k[2] + x[4])*x[4] + (-1)*k[8]*x[1] + (-1)*k[12]*x[1] + (-1)*k[13]*x[1]*x[2])/k[17],
  Diff(x[2], t) = (1*k[5]*x[1] + 1*k[6]*x[3]*x[1] + (-1)*k[9]*x[2])/k[17],
  Diff(x[3], t) = (1*k[7]*x[1] + (-1)*k[10]*x[3])/k[17],
  Diff(x[4], t) = ((-1)*k[1]/(k[2] + x[4])*x[4] + 1*k[4]*x[3] + (-1)*k[11]*x[4])/k[17],
  Diff(x[5], t) = 0 ]