Determine whether the following function is convergent or divergent? If convergent, what does it converge towards.
$$f(x)=-2\sum _{ n=-\infty }^{ \infty }{ \left( \frac { \left( -1 \right) ^{ n } }{ n } \right) } ·sin(nx)$$
Things I have tried
Determining whether it is convergent
So I started by using the Root test to test the convergence and I got 1 for the following expression from the sum,
$$a_n=\left( \frac { \left( -1 \right) ^{ n } }{ n } \right) ·sin(nx)$$
Hence the test is inconclusive. But I have a question on this, because wont I have to time my answer for $a_n$ with -2? Meaning when doing the Test, do I have to write the expression as,
$$-2 \cdot |a_n|^{1/n}$$
or as independent of -2.
$$|a_n|^{1/n}$$.
On the other hand, I also tried using another approach, where I have said that since we know that,
$$\frac{(-1)^n}{n}$$
is conditionally convergent, and therefore our sum should also be conditionally convergent. Is this a correct method? If so, then how can I write that in mathematical term.
The final part of the question, I do not know how can I find the value of the convergence. I mean towards what value does it converge. I mean,$\frac{(-1)^n}{n}$ converges towards $-log(2)$ but how can I find the value of the above function. It is the sin(nx) that has been confusing me. Any help will be great. Thank You.
EDIT The value it converges towards
So I have figured out how to determine whether it is convergent or not. But how can I determine the value it converges towards? Because I get the value of 1, but am sure that is wrong.