Datboiriley69 Datboiriley69
  • 22-06-2018
  • Mathematics
contestada

What is the sum of the geometric sequence four, 16, 64,... If there are eight terms

A)21,845
B) 43,690
C)65,535
D)87,380

Respuesta :

LammettHash
LammettHash LammettHash
  • 23-06-2018
[tex]S=4^1+4^2+4^3+\cdots+4^8[/tex]
[tex]4S=4^2+4^3+4^4+\cdots+4^9[/tex]
[tex]\implies4S-S=3S=4^9-4^1[/tex]
[tex]\implies S=\dfrac{4^9-4}3=87,380[/tex]
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