For what values of the variable does the series converge? Use the properties of geometric series to find the sum of the series when it converges.
10x + 20x^2 + 40x^3 + 80x^4 + ... sum = domain = (Give your domain as an interval or comma separated list of intervals; for example, to enter the region x < -1 and 2 < x ≤ 3, enter (-infinity,-1), (2,3].)