[ Eq(Derivative(x1, t), ((-1)*(k2*(k11 + k17*x8)*x1 - k1*x5*x2)*k21 + 1*k21*k4*k7*x4)/k21),
  Eq(Derivative(x2, t), (1*(k2*(k11 + k17*x8)*x1 - k1*x5*x2)*k21 + (-1)*(k3*(k15*x2 + k14*x3 + k10 + k16*x4)*x2 - k7*x3)*k21)/k21),
  Eq(Derivative(x3, t), (1*(k3*(k15*x2 + k14*x3 + k10 + k16*x4)*x2 - k7*x3)*k21 + (-1)*(k1*x5*x3 - k2*(k11 + k17*x8)*x4)*k21)/k21),
  Eq(Derivative(x4, t), (1*(k1*x5*x3 - k2*(k11 + k17*x8)*x4)*k21 + (-1)*k21*k4*k7*x4)/k21),
  Eq(Derivative(x5, t), 1*(x10*k12*x6 - k13*x5)*k21/k21),
  Eq(Derivative(x6, t), (-1)*(x10*k12*x6 - k13*x5)*k21/k21),
  Eq(Derivative(x7, t), (-1)*k21*((k5*(k15*x2 + k14*x3 + k10 + k16*x4) + k9)*x7 - k8*x8)/k21),
  Eq(Derivative(x8, t), 1*k21*((k5*(k15*x2 + k14*x3 + k10 + k16*x4) + k9)*x7 - k8*x8)/k21),
  Eq(Derivative(x9, t), (-1)*k6*(k15*x2 + k14*x3 + k10 + k16*x4)*x9*k21/k21),
  Eq(Derivative(x10, t), ((-1)*(x10*k12*x6 - k13*x5)*k21 + 1*k6*(k15*x2 + k14*x3 + k10 + k16*x4)*x9*k21)/k21) ]