Question

How do you find the sum of the infinite geometric series 1/7 + 1/28 + 1/112 + 1/448 + ...?

Answer 1

`4/21`

Explanation:

The sum of the geometric series
#a+ar+ar^2+ar^3+... =a/(1-r)#, when `|r|<1`,.
Here, `a=1/7 and r=1/4<1`.
So, the answer is `(1/7)/(1-1/4)=4/21`..