Thread: Series questions!

(3) / n sqrt(n)

not sure what test i should use for this problem!


-----------------------------------------------------

[( -1 )^n] * [3^(n-2)] / 2^n

i dont understand why i cannot use this root test for this problem...it seems to work out fine and i get the limit = 0 so since L < 1 then it should be convergent....but this is actually supposed to be divergent.



----------------------------------------------------------

10n+3 / n2^n

another one i'm not sure which test i should use

Originally Posted by lochnessmonster

(3) / n sqrt(n)

not sure what test i should use for this problem!


-----------------------------------------------------

[( -1 )^n] * [3^(n-2)] / 2^n

i dont understand why i cannot use this root test for this problem...it seems to work out fine and i get the limit = 0 so since L < 1 then it should be convergent....but this is actually supposed to be divergent.



----------------------------------------------------------

10n+3 / n2^n

another one i'm not sure which test i should use

I am having a hard time reading the first one my guess is that it is this



This is a p-series with



This is a geometric series or use the basic test for divergence!

For the last one I think this is the series



Use the limit comparison test with this is a convergent geometric series

Originally Posted by lochnessmonster

(3) / n sqrt(n)

Use the integral test.

[( -1 )^n] * [3^(n-2)] / 2^n

i dont understand why i cannot use this root test for this problem...it seems to work out fine and i get the limit = 0 so since L < 1 then it should be convergent....but this is actually supposed to be divergent.

Check your limit (it is not ) . The limit does not exist, so the series is divergent.

10n+3 / n2^n another one i'm not sure which test i should use

Use the ratio test.


Edited: Sorry, I didn`t see the previous post.