4.4. Let p(x) = x - c1xk-1 - c2xk-2 -...- CK, and let a be a double root of the polynomial p (this means that (x - o) can be factored from p). Show that the sequence an = n . an (n = 1,2,...) satisfies the following recurrence for all n > k: an = Clan-1 + C2an-2+ . . . + Ckan-k