Question

2. Find the sum of first six terms of the G.P. 5, 15, 45,...​

Answer 1

a=5,

r=3

sum of n terms in a gp= a(r power n --1)/(r--1)

sum of 6 terms = 5(3^5 --1)/(3--1) = 5*(243--1)/2 = 5*242/2 = 5*141 = 705

hope this helps :)