# How do you find the sum of the infinite geometric series 1/7 + 1/28 + 1/112 + 1/448 + ...?

$\frac{4}{21}$
a+ar+ar^2+ar^3+... =a/(1-r), when $| r | < 1$,.
Here, $a = \frac{1}{7} \mathmr{and} r = \frac{1}{4} < 1$.
So, the answer is $\frac{\frac{1}{7}}{1 - \frac{1}{4}} = \frac{4}{21}$..