SOLUTION: What is Sn of the geometric series with a1=-81, r=-2/3, and n=5? A)26 B) -39 C) -55 D)211

Algebra ->  Sequences-and-series -> SOLUTION: What is Sn of the geometric series with a1=-81, r=-2/3, and n=5? A)26 B) -39 C) -55 D)211      Log On


   

Question 855044: What is Sn of the geometric series with a1=-81, r=-2/3, and n=5?
A)26
B) -39
C) -55
D)211
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
S=a*(1 - r^n)/(1 - r)
S=-81*(1 - (-2/3)^5)/(1 - (-2/3))
S = -55
C) -55