Note: those marked with an asterisk I am not 100% confident in my answer/reasoning.

Please feel free to discuss the problems and my proposed solutions below!

2.1

Here is my proof for this problem:

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and here are my reasonings for each numbered step:

  1. Constant multiple property of logs.
  2. f = O(g) was given.
  3. Function composition of Big-O
    • log(n) = O(log(n) by identity property of Big-O.
    • f = O(g) was given.
  4. Multiplicative property of Big-O.
  5. Constant multiple property of Big-O.

Thus, A should be the right answer.

2.2

Because of the composition property of Big-O, the proposed statement is true. Answer choice A is definitely correct, and I believe D is just another way of stating what f = O(g) means mathematically. So both A and D are correct.

Turns out that my previous answer was incorrect. I was presented a counter example, f = 2n and g = n. Thus, A is not correct, and it should be C and D.

2.3

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A, C, E, D, B

2.4

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E, A, B, D, C

2.5

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A, E, C, B, D