(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

[tex]\frac{d^{2n}}{dx^{2n}}\cos x[/tex]

[tex]n \in N[/tex]

2. Relevant equations

[tex]\cos x=\sum^{\infty}_{k=0}(-1)^k\frac{x^{2k}}{(2k)!}[/tex]

3. The attempt at a solution

[tex]\frac{d^{2n}}{dx^{2n}}x^{2n}=(2n)![/tex]

But k is different that [tex]n[/tex]. I don't have a clue how to solve that.

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# Find derivative

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