关键词 > MTH2140/MTH3140
MTH2140/MTH3140 Real Analysis – Assignment 1 (2023)
发布时间:2023-06-10
Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit
MTH2140/MTH3140 Real Analysis – Assignment 1 (2023)
Due date: 10am on Monday 3 April
1. We consider two non-empty sets A and B, with A ⊂ R+ bounded above and B ⊂ (1.5, +∞) bounded below, and we define C = {z ∈ R : there exists x ∈ A and y ∈ B such that z = } .
C is therefore the set of all real numbers created as the division between any number in A and any number in B . Prove that sup(C) exists and that sup(C) = .
2. Consider the following statement: “if A,B are two non- empty sets, each one having a minimum, then A ∪ B has a minimum”. Determine if this statement is true or false. If it is true, give a proof. If it is false, provide a counter-example.
(Note: the solution is not very long and does not require the usage of complicated calculations; it can therefore be typed using plain text, with minimal mathematical notations, as per the instructions provided in the lecture notes . You do not have to present your solution this way, but it can help you train for the ”short response” questions in the final exam.)
3. Let u1 > ^5 and define u2 ,u3 ,u4 , ··· by the formula
un+1 = (un +
).
(a) Prove that (un )n∈N is a strictly decreasing sequence.
(b) Prove that (un )n∈N converges and the limit is ^5. Make sure you clearly state any theorem you invoke to establish this proof.
4. [MTH2140 only] Determine if the following series is convergent or divergent and justify your answer. 工 .
5. [MTH3140 only] Consider a strictly positive sequence (xn )n∈N .
(a) Show that the convergence of 之 xn implies the convergence of 之
.
(b) Show that the divergence of 之 xn implies the divergence of 之