Question

PLEASE HELP ASAP!!! CORRECT ANSWER ONLY PLEASE!!!

What is the sum of the first eight terms of the series?

(−800)+(−200)+(−50)+(−12.5)+...



Round the answer to two decimal places.

Answer 1

Hello there,

What is the sum of the first eight terms of the series?

(−800)+(−200)+(−50)+(−12.5)+...

Round the answer to two decimal places.

Answer: (C) -1066.65

Answer 2

Answer: (C) -1066.65

Explanation:

Given the sequence {-800, -200, --50, -12.5, ... , a₈} we know the following

• the first term (a₁) = -800
• the common ratio (r) =
  `-(1)/(4)`
• the number of terms (n) = 8

Input the information above into the Sum formula:

`S_n=(a_1(1-r^n))/(1-r)\\\\S_8=(-800(1-((1)/(4))^8))/(1-(1)/(4))\\\\\\.\quad =(-800(1-(1)/(65,536)))/((3)/(4))\\\\\\.\quad =(-800((65,535)/(65,536)))/((3)/(4))\\\\\\.\quad =((4)(-800)(65,535))/(3(65,536))\\\\.\quad =-1066.65`