Question

How to find the sum of n terms which are in G.P?

Answer 1

There's a formula 4 it which is given in the maths book.

Answer 2

the formula for sum of G.P is
$S_n= \frac{a(r^n-1)}{r-1)}$
if r>1
where a is the first term
   r is the common difference
   n is the number of terms
$S_n= \frac{a(1-r^n)}{1-r)}$
if r<1
$S_n= \frac{a}{1-r}$
if r<1 and n tends to infinity