Question

find the sum of the infinite geometric series 9+3+1+1/3+...

Answer 1

Sum of Infinite Geometric series is:

$\frac{a}{1-r}$

Where :

a= first term = 9

r= common ratio = 3/9 = 1/3 =1/3 /1 = 1/3

Replace:

$\frac{9}{1-\frac{1}{3}}\text{ =}\frac{9}{\frac{2}{3}}=\frac{27}{2}=13.5$