[ Eq(Derivative(x1, t), (1*k11*k1 + (-1)*k11*k2*x1 + (-1)*k11*k3*x1*x2 + (-1)*k11*k4*x1*x3)/k11),
  Eq(Derivative(x2, t), (1*k11*k5*k3*x1*x2 + (-1)*k11*(k2 + k6)*x2)/k11),
  Eq(Derivative(x3, t), (1*k11*k7*k4*x1*x3 + (-1)*k11*(k2 + k8)*x3)/k11) ]