EmmGreg3ibb
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what is the sum of a 7-term geometric series if the first term is −6, the last term is −24,576, and the common ratio is −4? −32,766 −19,662 19,662 32,766

Respuesta :

apologiabiology
sum of ggeo metric sequence is

Sn=[tex] \frac{a1(1-r^n)}{1-r} [/tex]

n=which term
a1=first term
r=common ratio


so
n=7
a1=-6
r=-4

Sn=[tex] \frac{-6(1-(-4)^7)}{1-(-4)} [/tex]
Sn=[tex] \frac{-6(1-(-16384))}{1+4} [/tex]
Sn=[tex] \frac{-6(1+16384)}{5} [/tex]
Sn=[tex] \frac{-6(16385)}{5} [/tex]
Sn=[tex] \frac{-98310}{5} [/tex]
Sn=-19662

answer is 2nd option os -19662



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