perplexus.info :: Calculus : Second derivative of a cosine product

Second derivative of a cosine product (Posted on 2024-02-27)

For natural number n, define f_n(x) as the product cos(x) * cos(2x) * cos(3x) * .... * cos(nx).

What is the smallest n such that |f_n''(0)| > 2024?

No Solution Yet Submitted by Brian Smith

Rating: 5.0000 (2 votes)

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Puzzle Thoughts

| Comment 3 of 5 |

the smallest n such that |f_n''(0)| > 2024 occurs at n=18

Posted by K Sengupta on 2024-02-27 14:02:08

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