# How do you find the sum of the infinite geometric series -2.5(-0.1)^(n - 1)?

The first term ${a}_{1} = - 2.5$ and common ratio $r = - 0.1$
${S}_{\infty} = {a}_{1} / \left(1 - r\right) = \frac{- 2.5}{1 - \left(- 0.1\right)} = \frac{- 25}{11} \approx - 2.2727$