Consider the following three claims — I.(n+k)m = Θ(nm) where k and m are…
2022
Consider the following three claims —
I.(n+k)m = Θ(nm) where k and m are constants.
II. 2n+1 =O(2n )
III. 22n =O(2n)
Which of the above statements are correct?
- A.
I and II
- B.
I and III
- C.
II and III
- D.
I, II and III
Attempted by 405 students.
Show answer & explanation
Correct answer: A
Consider the three claims:
I. (n + k)^m = Θ(n^m), where k and m are constants
II. 2^(n+1) = O(2^n)
III. 2^(2n) = O(2^n)
Evaluation:
Statement I: TRUE
Since k and m are constants, (n + k)^m can be expanded using the binomial theorem:
(n + k)^m = n^m + m·k·n^(m-1) + lower order terms.
The highest power term is n^m, and lower-order terms do not affect asymptotic growth. Hence, (n + k)^m grows at the same rate as n^m, so it is Θ(n^m).
Statement II: TRUE
We have 2^(n+1) = 2 · 2^n. This is just a constant multiple of 2^n. In Big-O notation, constant factors are ignored. Therefore, 2^(n+1) = O(2^n).
Statement III: FALSE
We have 2^(2n) = (2^2)^n = 4^n. This grows much faster than 2^n. {i.e. a^(bc) = (a^b)^c}
Consider the ratio: 2^(2n) / 2^n = 2^n → ∞ as n → ∞.
Since it is not bounded above by a constant multiple of 2^n, the Big-O relation does not hold.
Final Conclusion:
Statement I and II are correct, while Statement III is incorrect.