Find the sum of the series

Question

-4 + 1 -1/4 + 1/16 - 1/64 + 1/256 + ... .

Answer 1

A GS, with
a = -4
r = -1/4

sum(∞) = a/(1-r)
= -4/(1 -(-1/4) )
= -4/(5/4)
= -16/5 or -3.2