# series conv or div

• Mar 22nd 2009, 02:11 PM
twilightstr
series conv or div
series conv or div for sum (2 +(-1)^n)/(nsquarerootn)
• Mar 22nd 2009, 02:14 PM
o_O
Note that: $0 < 2 + (-1)^n \leq 3$

So use the comparison test noting that: $\frac{2 + (-1)^n}{n \cdot n^{\frac{1}{2}}} \ \leq \ \frac{3}{n^{\frac{3}{2}}}$
• Mar 22nd 2009, 03:17 PM
twilightstr
why isnt the series between 1 and 3 instead of 0 and 3