can you please do the whole problem. i.e write it in terms of X_t-1, X_t-2,... and Z_t-1, Z_t-2,....

3. (a) For the following SARIMA(p, d, q) x (P, D, Q) s models, specify parameters p, d, q, P, D, Q and s, and write corresponding equations: (i) SARIMA (2, 1, 1) x (0, 1, 1) 6, (ii) SARIMA(1, 1, 2) x (2, 0, 1)4. Hint: It is helpful to first write equations in the form (B) $(BS) (1 - B)(1 - BS)DXt = 0(B)O(BS) Zt, Zt ~ WN(0, oz), then proceed to rewrite the equations in the form that eliminates use of the backshift operator B