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MATH0051: Analysis 4 — Real Analysis

Resit coursework 2022

Answer all questions

1. Let X = (0, ∞) and

d(x,y) = I log ( ) I.

(i) Prove that (X,d) is a metric space;

(ii) Describe all convergent sequences in (X,d).

(iii) Describe all Cauchy sequences in (X,d).

(iv) Is this metric space complete?

Justify your answers.

2. Prove that

||x||∞  =  |xi |

defines a norm on Rn .


3. Let {an } be a sequence of positive real numbers such that an  → 0 as n → ∞ . Let fn (x) = (x + an )2 , x ∈ R. Does the sequence {fn } converge pointwise on R? If it does, what is the limit function?  Does the sequence {fn } converge uniformly on

R? Justify your answers.                                                                                        [10 marks]