Explore the series for absolute and conditional convergence

34 Views Asked by At

$$\sum_{k=1}^{\infty} \frac{(-1)^{k} k}{\sqrt{(k+1)(k+2)}} $$ I found that absolute series diverges

1

There are 1 best solutions below

0
On BEST ANSWER

Since you don't have$$\lim_{k\to\infty}\frac{(-1)^kk}{\sqrt{(k+1)(k+2)}}=0,\tag1$$the series diverges. And you don't have $(1)$ because$$\lim_{k\to\infty}\left\lvert\frac{(-1)^kk}{\sqrt{(k+1)(k+2)}}\right\rvert=1.$$