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$$\sum_{n=1}^\infty (-1)^n\frac{n}{10^n}$$

I am trying to show that $|a_{n+1}|$ is less than or equal to $|a_n|$

So I have $\frac{n+1}{10^{n+1}}$ less than or equal to $\frac{n}{10^n}$.

And then that $\lim_{n\to\infty} a_n = 0$

Both are supposedly true and makes the series convergent but when I do it I get not true for both conditions and then divergent for the series, which is wrong.

  • 0
    What do you mean "when I do it?" The series converges for precisely the reasons you said.2011-07-27
  • 0
    I've put your equations into LaTeX.2011-07-27

5 Answers 5