State whether the given geometric series have sums.
10. 1 + .1 + .01 + .001 + …
answer = Sum 1.1
12. 1 – 1/5 + 1/25 – 1/125 + …
Answer = Sum 5/8
10 r = 1/10
Sum = 1 / [ 1 - 1/10] = 1 / (9/10) = 10 / 9
12 r = -1/5
Sum = 1 / [ 1 - -1/5] = 1 / [ 6/5] = 5 / 6