Given: √7, √21, 3√7 ,... n terms.

Sum of n terms of a G.P. is given by: (a: First term of G.P, r: common difference of G.P, n: Number of terms of the G.P)

First term of the Given G.P (a) = √7

Common difference of the given G.P(r) = = √3

Number of terms(n): n

Let the sum of n terms be s

∴ The sum of n terms of the given sequence is: