[ Diff(x[1], t) = (1*k[2] + (-1)*k[4]*x[1]*(1 + x[1])*(1 + x[2])^2/(k[3] + (1 + x[1])^2*(1 + x[2])^2))/k[1],
  Diff(x[2], t) = (50*k[4]*x[1]*(1 + x[1])*(1 + x[2])^2/(k[3] + (1 + x[1])^2*(1 + x[2])^2) + (-1)*k[7]*x[2]*(1 + k[6]*x[2])*(1 + x[3])^2/(k[5] + (1 + k[6]*x[2])^2*(1 + x[3])^2))/k[1],
  Diff(x[3], t) = (1/50*k[7]*x[2]*(1 + k[6]*x[2])*(1 + x[3])^2/(k[5] + (1 + k[6]*x[2])^2*(1 + x[3])^2) + (-1)*k[8]*x[3])/k[1] ]