Question

Find the sum of the geometric series

a.
220/7
b.
286/13
c.
66
d.
32/5


Please select the best answer from the choices provided
A
B
C
D

Answer 1

D: 32/5

Explanation:

Given series is 8 -2 + 1/2 - 1/8+.....

to find the sum we use formula

`S_n = (a)/(1-r)`

where a is the first term

r is the common ratio

To find common ratio we divide second term by first term

`r= (-2)/(8) =(-1)/(4)`

a= 8

Now plug inthe values and find out the sum

`S_n = (a)/(1-r)`

`S_n = (8)/(1-(-1)/(4))`

`S_n = (8)/(1+(1)/(4))`

`S_n = (8)/((5)/(4))`

`S_n = 8*(4)/(5)`

sum = 32/ 5