+0  
 
0
55
1
avatar+588 

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

adore.nuk  Mar 6, 2018
Sort: 

1+0 Answers

 #1
avatar
+1

This is a Geometric Series, where:

F = First term = -8

R = Common Ratio = - 2.

N =Number of terms =7. Use the formula for GS

 

S = F x (1 -R^N) / ( 1 - R)

S = -8 x (1 - (-2^7)) / (1 - (- 2))

S = -8 x (1 - (-128)) / (1 + 2)

S = -8 x (1 + 128) / 3

S = -8 x (129 / 3)

S = -8 x 43

S = - 344

Guest Mar 6, 2018

10 Online Users

avatar
avatar
New Privacy Policy (May 2018)
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  Privacy Policy