How do you find the sum of 4(3/2)^(i-1)4(32)i1 from i=0 to 6?

1 Answer
Feb 18, 2018

2059/24205924

Explanation:

This is a geometric series sum_{i=0}^n ar^ini=0ari with first term

a = 4(3/2)^{-1}=8/3a=4(32)1=83

and common ratio r = 3/2r=32

The sum is

um_{i=0}^n ar^i = a{r^{n+1}-1}/{r-1} = 8/3 {(3/2)^7-1}/{3/2-1} = 8/3 {2187/128-1}/{1/2} = 16/{3\times 128}(2187-128)= 2059/24umni=0ari=arn+11r1=83(32)71321=832187128112=163×128(2187128)=205924