Question

how many terms of series on G.P. 2+6+18+.......must be taken to make the sum equal to 728​

Answer 1

Answer:

6 terms. .................

Answer 2

Use the formula for geometric series:
Sn= a(1-r)^n/(1-r)
R is the common ratio which is 3
a is the first term which is 2
Rearrange and solve to find n, which is 6