[ Eq(Derivative(x1, t), ((-1)*k13*(k1*x1*x3 - k9*x2) + 1*k13*k2*x2 + (-1)*k13*(k3*x1*x4 - k10*x5) + 1*k13*k4*x5 + (-1)*k13*(k5*x1*x3 - k11*x7) + 1*k13*k6*x7 + (-1)*k13*(k7*x1*x8 - k12*x9) + 1*k13*k8*x9)/k13),
  Eq(Derivative(x2, t), (1*k13*(k1*x1*x3 - k9*x2) + (-1)*k13*k2*x2)/k13),
  Eq(Derivative(x3, t), ((-1)*k13*(k1*x1*x3 - k9*x2) + (-1)*k13*(k5*x1*x3 - k11*x7))/k13),
  Eq(Derivative(x4, t), (1*k13*k2*x2 + (-1)*k13*(k3*x1*x4 - k10*x5))/k13),
  Eq(Derivative(x5, t), (1*k13*(k3*x1*x4 - k10*x5) + (-1)*k13*k4*x5)/k13),
  Eq(Derivative(x6, t), (1*k13*k4*x5 + 1*k13*k8*x9)/k13),
  Eq(Derivative(x7, t), (1*k13*(k5*x1*x3 - k11*x7) + (-1)*k13*k6*x7)/k13),
  Eq(Derivative(x8, t), (1*k13*k6*x7 + (-1)*k13*(k7*x1*x8 - k12*x9))/k13),
  Eq(Derivative(x9, t), (1*k13*(k7*x1*x8 - k12*x9) + (-1)*k13*k8*x9)/k13) ]