# Big Theta Notation...

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• May 11th 2013, 04:42 PM
RatchetTheLombax
Big Theta Notation...
Select a theta notation for f(n) + g(n)

f(n) = 6n^3+2n^2+4, g(n) = Θ(n ln n

Would the theta notation be Θ(n^3) or Θ(n^k)?
• May 13th 2013, 12:25 PM
emakarov
Re: Big Theta Notation...
Quote:

Originally Posted by RatchetTheLombax
Would the theta notation be Θ(n^3) or Θ(n^k)?

What is k? Are you claiming that f(n) + g(n) = Θ(n^k) for some k? This is true, but it certainly carries less information that saying that f(n) + g(n) = Θ(n^3). Whether you are allowed to use such non-specific answer depends on the problem and course requirements. You could as well say that f(n) + g(n) = Θ(f(n) + g(n)) or f(n) + g(n) = Θ(h(n)) for some h; that would be correct but carry no information at all.

The correct answer is probably Θ(n^3).
• May 13th 2013, 06:35 PM
zzephod
Re: Big Theta Notation...
Quote:

Originally Posted by RatchetTheLombax
Select a theta notation for f(n) + g(n)

f(n) = 6n^3+2n^2+4, g(n) = Θ(n ln n

Would the theta notation be Θ(n^3) or Θ(n^k)?

If the latter it would only be true if k=3.

.