Question

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

Answer 1

Hello there,

What is the sum of the first 7 terms of the series −8 +16 −32 + 64−... ?

Answer: -258

Answer 2

Answer: -258

Step-by-step explanation:

Given the sequence {-8, 16, -32, 64, ... , a₇} we know the following

• the first term (a₁) = -8
• the common ratio (r) = -2
• the number of terms (n) = 7

Input the information above into the Sum formula:

$S_n=\dfrac{a_1(1-r^n)}{1-r}\\\\S_7=\dfrac{-8(1-(-2)^7)}{1-(-2)}\\\\.\quad =\dfrac{-8(1-(-128))}{1+3}\\\\.\quad =\dfrac{-8(129)}{4}\\\\.\quad =-2(129)\\\\.\quad =-258$