Question

Find the Sum

Answer 1

looks like a geometric series to me ^.^
what do you think?

Answer 2

ok but how do I find the sum?

Answer 3

there's a formula ^.^
But first, I want you to tell me a few things: its first term and its common ratio :D

Answer 4

Try performing an index shift
Let n = i - 1
i = n + 1

Answer 5

Then apply the formula

Answer 6

This is the formula:
\[\Large \frac{a(1-r^n)}{1-r}\]
where a is the first term, r is the common ratio, and n is the number of terms you add :)

Answer 7

got it it's 511 ty!!!!!!!

Answer 8

That's great ^.^