# Math Help - summation exponential functions

1. ## summation exponential functions

Dear members,

see attached pdf file.Can you help me to prove these sums.

Thank you

Gilbert

2. ## Re: summation exponential functions

Gilbert

The first series is the sum of infinite terms of a geometric sequence whose first term is a = e^(-z) and ratio also r = e^(-z) this sequence is a decreasing sequence
and as you probably know the sum of infinite terms os such a sequence is given by the formula S =a/1-r .
Apply this formula and you will have the first summ in front of you...good luck with the other...don't expect every thing from us...do some homework as well.

MINOAS

3. ## Re: summation exponential functions

Gilbert

I forgot to mention that the second series is almost similar to the first....maybe you have to split it in two series....it is really easy. the solution is in one line