Consider the ARMA(2,2) process given by Xt = 0.4Xt-1+0.45Xt 2tettet-1+0.25et-2 withet ~ WN(0, o?). (i) Show that the process simplifies into an ARMA(1, 1) and that it is causal and invertible. (ii) Obtain the Wold representation of X