{ diff(x1, t) = (1*k10*k1*x1 + (-1)*k10*(k2*x2*x1 + k3*x1*x1))/k10,
  diff(x2, t) = (1*k10*(k4 + k6*x2*x1) + (-1)*k10*(k5*x2 + k7*k2*x2*x1))/k10,
  diff(x3, t) = (1*k10*k8*x1 + (-1)*k10*k9*x3)/k10 }