Evaluate the geometric Series or state that it diverges

Question

lower bound k= 1 upper bound = infinity

E (sum symbol) E 5(-1/6)^(5k)

I know it converges but im not sure to what

Answer 1

a = 5(-1/6)^5
Note that (-1/6)^(5k) = ((-1/6)^5)^k, so
r = (-1/6)^5

S = a/(1-r) = (5(-1/6)^5)/(1-(-1/6)^5) = -5/7777