[ Diff(x[1], t) = k[3] - (k[2] + k[1]*x[2])*x[1],
  Diff(x[2], t) = x[3]*k[4]*x[1]^2/(k[5] + x[1]^2) - k[6]*x[2],
  Diff(x[3], t) = ((-k[7]) + k[8]*x[1] - k[9]*x[1]^2)*x[3] ]