Question

Help with summation notation? I would really appreciate help on this!

Answer 1

http://imgur.com/RTBGlBp.jpg

Here's what I got for the first one:
10000
Σ -10K
k=1
I think that may be correct but I would like some extra reassurance.

As for number two, I am lost on that one and would really appreciate any help. They are all factors of five, I know that much. But what would be the summation notation?

Answer 2

for the first one:

\[\sum_{k=0}^{k=4}(-10)^{k}\]

Answer 3

second:

\[\sum_{k=1}^{5}\frac{ 1 }{ 5k }\]