precalculus math help

Question

find the number of terms for the following series:

Answer 1

3, 6,12,24,48,96, 192

seven terms in the sequence, 3 is first, 192 is 7th, each term twice the previous

sum of the series =3+6+12+24+48+96+192 = 381

or use the formula for sum of a geometric series

with

r=2,= common ratio; N=7= number of terms in the series

SN = A(1-r^N)(1-r) = 3(1-2^7)/(1-2) = 3(128) = 381