- #1

ILoveBaseball

- 30

- 0

[tex]\sum_{n=1}^\infty \frac{2^n+6^n}{9^n}[/tex] or can be written as...

[tex]\sum_{n=1}^\infty \frac{8^n}{9^n}[/tex]

[tex] A_1 = 8/9, A_2 = 64/81, A_3 = 512/729 [/tex]

common ration (r)= 8/9

first term (a)= 8/9

so plugging everything i know into the geometric series formula:

[tex] \frac {a}{1-r}[/tex]

i get... 8

but it's wrong, and i don't see why