[ Eq(Derivative(x1, t), (-1)*k1*(k2*x1*x3 - k3*x2)/k1),
  Eq(Derivative(x2, t), (1*k1*(k2*x1*x3 - k3*x2) + (-1)*k1*(k4*x2*x4 - k5*x5))/k1),
  Eq(Derivative(x3, t), (-1)*k1*(k2*x1*x3 - k3*x2)/k1),
  Eq(Derivative(x4, t), (-1)*k1*(k4*x2*x4 - k5*x5)/k1),
  Eq(Derivative(x5, t), 1*k1*(k4*x2*x4 - k5*x5)/k1) ]