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Determine the value of constants C and k, if any, such that the function f(x)=17x+11 is O(x²).

(a) C=18,k=1
(b) C=18,k=11
(c) C=1,k=1
(d) C=1,k=17
(e) C=18,k=17

1 Answer

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Final answer:

The correct constants C and k such that the function f(x)=17x+11 is O(x²) are C=18 and k=1, satisfying the inequality 17|x| + 11 ≤ C|x²| for all x ≥ k.

Step-by-step explanation:

The question is asking to find the constants C and k such that the function f(x) = 17x + 11 is O(x²) ('big O notation' representing the upper bound of the growth rate of the function). To show that f(x) is O(x²), we need to find a positive constant C and a value k such that for all x ≥ k, it holds that |f(x)| ≤ C|x²|. Substituting f(x) into the inequality gives us 17|x| + 11 ≤ C|x²|. It is clear that for x ≥ 1, 17x + 11 is always less than any C times x², if C is chosen large enough. For instance, C = 18 and k = 1 satisfy this inequality because 17x + 11 ≤ 18x² whenever x ≥ 1. Therefore, option (a) C=18,k=1 is the correct answer.

User Steeve Pitis
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