Question

What is the sum of the geometric sequence 1, 3, 9, … if there are 10 terms

Answer 1

the first term a1 = 1
with ratio r = a2/a1 = 3/1 = 3

to get the sum of that series
use the formula :
S10 = a1(r^n - 1)/(r - 1)

Answer 2

i mean
Sn = a1(r^n - 1)/(r - 1)
with n = 10

Answer 3

Do you know the formula for a geometric progression?
It's \[ar ^{n-1}\]
Here, a = the first in the series = 1
r = the ratio = 3/1 = 9/3 = 3
n = 10
Now plug in the values.

Answer 4

These are my choices

29,524

55,987

87,381

88,573

Answer 5

therefore, calculate this
S10 = 1(3^10 - 1)/(3 - 1) = ...

Answer 6

got it ?

Answer 7

I got 59047.7
????

Answer 8

I suck at math so much!

Answer 9

Wait its 29.524!

Answer 10

finally, u got it :)
yes, it is 29,524

Answer 11

Thank you

Answer 12

you're welcome