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