I want to calculate the infinite sum of the series below.
$$\sum_{k=2}^{\infty} \frac{2^{2k-1}}{5^{k+3}}$$
But unfortunately, I have no idea how to even start. Can I somehow use the formula of geometric series?
$$\sum_{k=2}^{\infty} ar^{k} = \frac{a}{1-r}$$
If I cannot, how should I solve the problem?
Thanks.