Question

What is the sum of the geometric sequence –4, 24, –144, … if there are 7 terms?

a 308,829
b –159,964
c –411,772
d 119,973

Answer 1

u know the formula ?

Answer 2

Sn = a0(1-r^n)/(1-r)

Answer 3

find r by dividing to successive terms . eg ->(24/-4) = -6

Answer 4

I don't know

Answer 5

a0 = first term = -4

Answer 6

what do u fail to understand ?

Answer 7

I honestly just need the answer

Answer 8

okay wait

Answer 9

just plug in the values rebercca !

Answer 10

\[\Large \sum_{k=1}^{7}\left( -4 \right)\left( -6 \right)^{k-1}=\huge {-4\left( 1-(-6)^7\right) \over 1-(-6)}\]

Answer 11

soooo

Answer 12

use ur calculator or solve manually .

Answer 13

I got 223948

Answer 14

it has to be negative...

Answer 15

Just kidding I got -159964

Answer 16

Thanks