Question

The sum of a geometric series is -2044. If the first term is -4 and the common ratio is 2, what is the final term in the sequence?

Answer 1

Sn = a[r^n-1]/r-1

Answer 2

use this and find n

Answer 3

Wait @Yahoo!

Answer 4

then an = a*r^(n-1)

Answer 5

Why @waterineyes any mistake

Answer 6

Sorry my mistake...

Ha ha ha..

Answer 7

\[-2044 = -4[2^n -1]/(2-1)\]

Answer 8

511 = 2^n - 1

510 = 2^n

Answer 9

find n??

Answer 10

\(-2044 = -4. \frac{2^{n}-1}{2-1}\)

\(-2044 = -4. (2^{n}-1)\)

\(511 = 2^{n}-1\)

\(512 = 2^{n}\)

\(2^9 = 2^{n}\)

9=n

Answer 11

512

Answer 12

sorry 512 = 2^n

Answer 13

now n = 9

Answer 14

subs in an = a * r^(n-1)

Answer 15

\[\large 2^n = 512 \implies 2^n = 2^9 \implies \color{green}{n = 9}\]

Answer 16

an = -4 * 2^8

Answer 17

you can replace n here by 9 @Yahoo!

Answer 18

256 * -4 = -1024

Answer 19

lol thanks!

Answer 20

Welcome