Question

Find the sum of the infinite geometric series 8 + 4 + 2 + 1 +...

Answer 1

Rule

\[\Large \sum_{k=1}^{\infty}a*r^{k-1} = \frac{a}{1-r}\]

if and only if |r| < 1. Since r = 0.5, that makes |r| < 1 true, which allows us to use the formula

Answer 2

I'm confused, do I used that equation to find the sum? If so what is a?

Answer 3

I posted what 'a' was in my second post above

Answer 4

a = first term

Answer 5

a = 8 is the first term
r = 0.5 is the common ratio

you use \[\Large S = \frac{a}{1-r}\]

Answer 6

So the sum is 16?

Answer 7

Yes.

Answer 8

yep S = 16