[ Eq(Derivative(x1, t), 1*k3*(k7*x5 - k6*x1*x6)/k3/k3),
  Eq(Derivative(x2, t), (-1)*k3*(k13*x2*x8 - k12*x3)/k3/k3),
  Eq(Derivative(x3, t), ((-1)*k3*(k9*x3 - k8*x4)/k3 + 1*k3*(k13*x2*x8 - k12*x3)/k3)/k3),
  Eq(Derivative(x4, t), ((-1)*k3*(k5*x4 - k4*x5)/k3 + 1*k3*(k9*x3 - k8*x4)/k3)/k3),
  Eq(Derivative(x5, t), (1*k3*(k5*x4 - k4*x5)/k3 + (-1)*k3*(k7*x5 - k6*x1*x6)/k3)/k3),
  Eq(Derivative(x6, t), (1*k3*(k7*x5 - k6*x1*x6)/k3 + (-1)*k3*(k11*x6 - k10*x7*x8)/k3)/k3),
  Eq(Derivative(x7, t), 1*k3*(k11*x6 - k10*x7*x8)/k3/k3),
  Eq(Derivative(x8, t), (1*k3*(k11*x6 - k10*x7*x8)/k3 + (-1)*k3*(k13*x2*x8 - k12*x3)/k3)/k3) ]