(a) For all n E N and a # 0, show that an k=1 (b) For a sequence (Xn) in R, suppose that there exists an b e (0, 1) such that (x+1 - Xml s b" for all n E N. Use part (a) to prove that X - x for some x E R. Note: If0 1. Then use part (a), since a > 1 + 0