Show the series $ \sum_{j=1}^{\infty} \frac{(2^j)+ j}{(3^j) - j} $ converges
Show the following series converges
$$ \sum_{j=1}^{\infty} \frac{(2^j)+ j}{(3^j) - j} . $$
I tried to use the comparison test and tried to compare it with the series of $\dfrac{2^j}{3^j}$ because this is the geometric series. However, $\dfrac {2^j}{3^j}$ is smaller than $\dfrac{2^j+j}{3^j-j}$, so by comparison test, the series $\sum_{j=1}^{\infty}\dfrac{2^j}{3^j}$ converges does NOT indicate that the series $\sum_{j=1}^{\infty}\dfrac{2^j+j}{3^j-j}$ converges... Thus I'm confused. Thanks!
Thanks!
Solution 1:
A related problem. The answer is correct and the downvote is misleading
Hint: You can make comparison test with the series
$$ \sum_{j=1}^{\infty} \left(\frac{2}{3}\right)^{j}. $$
Added: Here is the result you need
Suppose $\sum_{n} a_n$ and $\sum_n b_n $ are series with positive terms, then
if $\lim_{n\to \infty} \frac{a_n}{b_n}=c>0$, then either both series converge or diverge.
In your case the limit
$$ \lim_{n\to \infty} \frac{a_n}{b_n} = 1 > 0. $$
So, you can conclude.