[ Eq(Derivative(x1, t), (1*k9*k3*x3 + (-1)*k9*k1*x1 + (-2)*k9*k6*x1*(x1 - 1)/2*x4 + 2*k9*k8*x6)/k9),
  Eq(Derivative(x2, t), (1*k9*k4*x4 + (-1)*k9*k2*x2 + (-2)*k9*k5*x2*(x2 - 1)/2*x3 + 2*k9*k7*x5)/k9),
  Eq(Derivative(x3, t), ((-1)*k9*k5*x2*(x2 - 1)/2*x3 + 1*k9*k7*x5)/k9),
  Eq(Derivative(x4, t), ((-1)*k9*k6*x1*(x1 - 1)/2*x4 + 1*k9*k8*x6)/k9),
  Eq(Derivative(x5, t), (1*k9*k5*x2*(x2 - 1)/2*x3 + (-1)*k9*k7*x5)/k9),
  Eq(Derivative(x6, t), (1*k9*k6*x1*(x1 - 1)/2*x4 + (-1)*k9*k8*x6)/k9),
  Eq(Derivative(x7, t), ((-1)*k9*k3*x3 + 1*k9*k1*x1)/k9),
  Eq(Derivative(x8, t), ((-1)*k9*k4*x4 + 1*k9*k2*x2)/k9) ]