[ Eq(Derivative(x1, t), ((-1)*k11*k1*x5*x1 + (-1)*k11*(k2*x6*x1 - k3*x4))/k11),
  Eq(Derivative(x2, t), (1*k11*k1*x5*x1 + (-1)*k11*(k5*x2 + k2*x6*x2) + (-1)*k11*k4*x2)/k11),
  Eq(Derivative(x3, t), (1*k11*(k5*x2 + k2*x6*x2) + (-1)*k11*k4*x3)/k11),
  Eq(Derivative(x4, t), 1*k11*(k2*x6*x1 - k3*x4)/k11),
  Eq(Derivative(x5, t), (1*k11*(k6*x2 + (1 - k7)*k6*x3) + (-1)*k11*k8*x5)/k11),
  Eq(Derivative(x6, t), (1*k11*k9*k6*(x2 + x3) + (-1)*k11*k8*x6)/k11) ]