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

Question

raden · Answer

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)

raden · Answer

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

anonymous · Answer

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.

anonymous · Answer

These are my choices

 29,524

 55,987

 87,381

 88,573

raden · Answer

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

raden · Answer

got it ?

anonymous · Answer

I got 59047.7
 ????

anonymous · Answer

I suck at math so much!

anonymous · Answer

Wait its 29.524!

raden · Answer

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

anonymous · Answer

Thank you

raden · Answer

you're welcome