jerodelacruz2021
Answered

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find the sum of the first 7 terms of the geometric sequence : 3,9,27,81,...

(with solution)

PA HELP POOO THANKSSSS

Sagot :

Answer:

3279

Step-by-step explanation:

The sum to n terms of a geometric sequence is

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

where a is the first term and r the common ratio

Here a = 2 and r = a₂ ÷ a₁ = 9 ÷ 3 = 3 , then

S₇ = [tex]\frac{3(3^7-1)}{3-1}[/tex] = [tex]\frac{3(2187-1)}{2}[/tex] = 1.5 × 2186 = 3279

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