Suppose (X, : t E Z) is such that X, = b0 + blt + bzl'2 + K, for some constants b0 and [)2 where (K 2 t E Z) is a mean zero stationary process. . (3) Determine whether {x,} is stationary. o (a) Let V be the difference operator. What is VXI . (c) Determine the minimum value k that makes VkX, stationary (prove your claim)