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