[ Diff(x[1], t) = (1*k[8]*k[1]*k[2] + (-1)*k[8]*k[3]*x[1] + (-1)*k[8]*k[4]*x[2]*x[1])/k[8],
  Diff(x[2], t) = (1*k[8]*k[5]*k[2]*delay(x[1], k[7]) + (-1)*k[8]*k[6]*x[2])/k[8] ]