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