the sum of an infinite geometric series with first term a and common ratio r < 1 is given by.

The sum of a given infinite geometric series is

, and the common ratio is

What is the second term of this series?

by pluging the info given i got for an a value of

which is not the value of the second term but that is where i don't understand how you find out what the second term is.

if

then

the ans for the second term is

how did they get this. I looked at examples from several books but still ?

thnx ahead for help