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