[ Eq(Derivative(x1, t), ((-1)*x1*k8*k3*k2 + (-1)*x1*x4*k4*k2 + 1*x3*k7*k2)/k2),
  Eq(Derivative(x2, t), 0),
  Eq(Derivative(x3, t), (1*k8*x4*k5*k2 + (-1)*x3*k7*k2)/k2),
  Eq(Derivative(x4, t), (1*x1*k8*k3*k2 + (-1)*x1*x4*k4*k2 + 1*k8*x4*k5*k2 + (-2)*x4**2*k6*k2)/k2),
  Eq(Derivative(x5, t), 0) ]