inessafamina64 inessafamina64
  • 21-02-2021
  • Mathematics
contestada

Find the seventh term of the geometric sequence 1, 2, 4, ... and the sum of the first seven terms. t7= S7=

Respuesta :

reeserl reeserl
  • 21-02-2021

Answer:

Seventh term is 64

Sum of the first seven terms is 127

Step-by-step explanation:

The common ratio is 2

[tex]a_{n} = a_{1} r^{n - 1}[/tex]    

n = 7 and the first term is 1.  So,

[tex]a_{7} = 1(2^{7 - 1} ) = 2^{6} = 64[/tex]

Seventh term is 64

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

[tex]S_{7} = \frac{1(2^{7} -1)}{2 - 1}[/tex]

    [tex]= \frac{128 - 1}{1} = 127[/tex]

Sum of the first seven terms is 127

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