[ Diff(x[1], t) = (-1)*k[11]*k[2]*x[1]/k[11],
  Diff(x[2], t) = (1*k[11]*k[2]*x[1] + (-1)*k[11]*k[2]*x[2])/k[11],
  Diff(x[3], t) = (1*k[11]*k[2]*x[2] + (-1)*k[11]*k[10]*x[3])/k[11],
  Diff(x[4], t) = (1*k[11]*k[8] + (-1)*k[11]*k[5]*k[7]^k[8]/(k[7]^k[8] + x[5]^k[8])*x[4]*x[3])/k[11],
  Diff(x[5], t) = (1*k[11]*k[6]*x[4] + (-1)*k[11]*k[6]*x[5])/k[11] ]