bm42400
contestada

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

Respuesta :

Answer:

D: 32/5

Step-by-step explanation:

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

to find the sum we use formula

[tex]S_n = \frac{a}{1-r}[/tex]

where a is the first term

r is the common ratio

To find common ratio we divide second term by first term

[tex]r= \frac{-2}{8} =\frac{-1}{4}[/tex]

a= 8

Now plug inthe values and find out the sum

[tex]S_n = \frac{a}{1-r}[/tex]

[tex]S_n = \frac{8}{1-\frac{-1}{4}}[/tex]

[tex]S_n = \frac{8}{1+\frac{1}{4}}[/tex]

[tex]S_n = \frac{8}{\frac{5}{4}}[/tex]

[tex]S_n = 8*\frac{4}{5}[/tex]

sum = 32/ 5