Question

Find the 6th partial sum of

Answer 1

\[\sum_{i=1}^{\infty}7(4)^{i=1}\]

Answer 2

@perl @agent0smith

Answer 3

this is pretty simple - just add up the first 6 terms.

Answer 4

if you don't want to do that, use the formula for geometric series.

Answer 5

whats the formula?

Answer 6

\(\Huge a\frac{1-r^n}{1-r}\)
a the start term, r is the common ratio

Answer 7

the thing you NEED to note is your indexing.

Answer 8

and is n the amount a terms?

Answer 9

is that i -1