Question

The sum of series $9,3,1,\frac{1}{3},.....$ is

Answer 1

The given series $9,3,1,\dots$ is in GP

With common ratio $\frac{3}{9}=\frac{1}{3}$

$S_{\infty }=\frac{a}{1-r}\frac{9}{1-\frac{1}{3}}=\frac{27}{2}$