Introduction to Complexity Theory/Big O Algorithm Analysis/Quiz

{Which of the following is the most efficient? - $$O\left(2^{n}\right)$$ + $$ O\left(\log\left(n\right)\right)$$ - $$ O\left(n^{3}\right)$$ - $$ O\left(4n^{3}\right)$$
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{In how many steps would the binary search algorithm halt if it were to search for the value $$17$$, in the set $$S=\left\{2,3,5,7,11,13,17,19,23\right\}$$? { 2 | two | Two | TWO | tWo | twO | tWO | TwO | TWo }
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{What is the big O of the algorithm mentioned in the previous question? + $$O\left(\log\left(n\right)\right)$$ - $$ O\left(n\right)$$ - $$ O\left(c\right)$$ - $$O\left({n \log\left(n\right)}\right)$$
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