For what values of x do $sum_n=1^infty frac(-1)^n-1cos(nx)n$ and $sum_n=1^infty frac(-1)^n-1sin(nx)n$ converge?

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Is there a way to determine the values of x for which $$sum_n=1^infty frac(-1)^n-1cos(nx)n$$ and $$sum_n=1^infty frac(-1)^n-1sin(nx)n$$ converge? I could not come up with an answer myself and found no other mention of series like these.







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  • Do you know Dirichlet's test? Try to write sine and cosine using exponentials.
    – 4-ier
    Aug 23 at 1:44














up vote
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down vote

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Is there a way to determine the values of x for which $$sum_n=1^infty frac(-1)^n-1cos(nx)n$$ and $$sum_n=1^infty frac(-1)^n-1sin(nx)n$$ converge? I could not come up with an answer myself and found no other mention of series like these.







share|cite|improve this question




















  • Do you know Dirichlet's test? Try to write sine and cosine using exponentials.
    – 4-ier
    Aug 23 at 1:44












up vote
0
down vote

favorite
2









up vote
0
down vote

favorite
2






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Is there a way to determine the values of x for which $$sum_n=1^infty frac(-1)^n-1cos(nx)n$$ and $$sum_n=1^infty frac(-1)^n-1sin(nx)n$$ converge? I could not come up with an answer myself and found no other mention of series like these.







share|cite|improve this question












Is there a way to determine the values of x for which $$sum_n=1^infty frac(-1)^n-1cos(nx)n$$ and $$sum_n=1^infty frac(-1)^n-1sin(nx)n$$ converge? I could not come up with an answer myself and found no other mention of series like these.









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asked Aug 23 at 1:25









Alex Carlson

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  • Do you know Dirichlet's test? Try to write sine and cosine using exponentials.
    – 4-ier
    Aug 23 at 1:44
















  • Do you know Dirichlet's test? Try to write sine and cosine using exponentials.
    – 4-ier
    Aug 23 at 1:44















Do you know Dirichlet's test? Try to write sine and cosine using exponentials.
– 4-ier
Aug 23 at 1:44




Do you know Dirichlet's test? Try to write sine and cosine using exponentials.
– 4-ier
Aug 23 at 1:44















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