Math 534A Practice Test 2: Solutions to Various Mathematical Problems, Exams of Mathematics

Solutions to three mathematical problems from math 534a practice test 2. The problems involve proving the existence of an increasing sequence of distinct integers, finding the interior, closure, boundary, accumulation points, and determining the openness, closedness, compactness, and connectedness of various sets. Additionally, there is a problem to determine if a statement is true or false.

Typology: Exams

Pre 2010

Uploaded on 03/28/2010

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Math 534A Practice Test 2
Please write up solutions to the following three problems on separate sheets of your own
paper using one side only and labeling each sheet with your name, the problem number, and
numbering the pages for each problem.
Example:
Jane Doe
page 2 of Problem 2A
1. Prove that there exists an increasing sequence of distinct integers n1, n2, ..., nk, ... such
that limk→∞ sin(nk) exists.
2. For each of the following sets, find the
interior
closure
boundary
set of accumulation points
In addition please decide whether the set is
open
closed
compact
connected
a. [a, b]
b. ZZ
c. ]2,3]
d. {x|x= 3 + (1)n5,for some nNN}
e. {1,3,2.7}
f. The rationals in [0,1].
1
pf2

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Math 534A Practice Test 2 Please write up solutions to the following three problems on separate sheets of your ownpaper using one side only and labeling each sheet with your name, the problem number, and numbering the pages for each problem. Example: Jane Doepage 2 of Problem 2A

1.that lim Prove that there exists an increasing sequence of distinct integers n 1 , n 2 , ..., nk, ... such k→∞ sin(nk) exists.

  1. For each of the following sets, find the
    • interior
    • closure
    • boundary
    • set of accumulation points

In addition please decide whether the set is

  • open
  • closed
  • compact
  • connected
  • a. [a, b]
  • b. ZZ
  • c. ]2, 3]
  • d. {x|x = 3 + (−1)n 5 , for some n ∈ NN}
  • e. { 1 , 3 , − 2. 7 }
  • f. The rationals in [0,1]. 1
  • g. {(x, y) ∈ IR^2 | |x| + |y| = 1}
  • h. ∪∞ n=1[− 1 , 1 /n[
  • i. {(x, y) ∈ IR^2 | x^2 + y^2 ≤ 1 }
  • j. {(x, y) ∈ IR^2 | |x| ≤ 1 }
  1. Determine by proof or counterexample the truth of the following statement: (A is compact in IR^2 ) ⇒ (IR^2 − A is connected).