Question

Which summation formula represents the series below?

Answer 1

12 - 24 + 48 - 96 = -160

Explanation:

12 - 24 = -12

-12 + 48 = 36

36 - 96 = -60

Answer 2

we are given

`12-24+48-96`

we can see that

total number of terms is 4

so, n=4

first term is 12

`a_1=12`

`a_2=-24`

now, we can find common ratio

`r=(-24)/(12)`

`r=-2`

now, we can find nth term

`a_n=a_1 (r)^(n-1)`

`a_n=12 (-2)^(n-1)`

so,

option-B.........Answer