Identify the following models in ARIMA (p, d, q) notation and determine whether they are stationary and/or invertible. Please show all the steps how to find the "d"-difference. Notes. Y 1.6Y-1-0.5-2 +et+0.2e-1+0.7e1-2 ARIMA(p, 1, q) model Let W = VY = Y- Y-1 then W =W-1+2W-2++pWt-p +-0-1-2-2---Oget-q or Y-Y (Y-Y-2) + + p (Y-p-Y-p-1) +et-Oet-1-0lt-2--- Oqt-q which can be rewritten as Y = (1+)+(-1)++ (p p 1) p-p-p-1 P -Oger a