# Am i doing right for these two question

1. Apr 24, 2007

### okevino

see attachment
thanks.

#### Attached Files:

• ###### convergence2.JPG
File size:
10.1 KB
Views:
77
2. Apr 24, 2007

### quasar987

That a_n-->0 in $$\sum a_n$$ does not imply that the series is convergent. You should re-read that theorem in your notes/book more carefully to see what it's actually saying.

3. Apr 24, 2007

### HallsofIvy

lim an= 0 is a necessary condition that
$$\Sigma a_n$$
converge, not a sufficient condition!

The first one "compares" to the sum of 1/n which does NOT converge.