For each of the following series, tell whether or not you can apply the 3-condition test (i.e. the alternating series test). Enter D if the series diverges by this test, C if the series converges by this test, and N if you cannot apply this test (even if you know how the series behaves by some other test).
1. $\displaystyle \sum_{n=2}^\infty \frac{(-1)^{n}(n^{4}+2n)}{n^{3} -1}$
2. $\displaystyle \sum_{n=1}^\infty \frac{(-1)^{n}(n^{3}+1)}{n^{3}+7}$
3. $\displaystyle \sum_{n=1}^\infty \frac{(-1)^{n} \cos(n)}{n^2}$
4. $\displaystyle \sum_{n=1}^\infty \frac{(-1)^n}{n^5}$
5. $\displaystyle \sum_{n=1}^\infty \frac{(-1)^{n}(n^{3}+1)}{n^{4}+1}$
6. $\displaystyle \sum_{n=1}^\infty \frac{(-1)^{n}(n^{10}+1)}{e^n}$