How do you find #S_n# for the geometric series #a_1=5#, r=2, n=14? Precalculus Series Sums of Geometric Sequences 1 Answer Cem Sentin Mar 16, 2018 #163835# Explanation: According to #S_n=a_1*[r^(n+1)-1]/(r-1)# formula, #S_15=5*(2^15-1)/(2-1)# =#163835# Answer link Related questions What is a sample problem about finding the sum of a geometric sequence? What is the formula for the sum of a geometric sequence? What is a sample problem about finding the sum of a geometric sequence? How do I find the sum of the geometric sequence #3/2#, #3/8#? What is the sum of the geometric sequence 3, 15, 75? What is the sum of the geometric sequence 8, 16, 32? How do I find the sum of the geometric series 8 + 4 + 2 + 1? How do you find the sum of the following infinite geometric series, if it exists. 2 + 1.5 +... How do you find the sum of the first 5 terms of the geometric series: 4+ 16 + 64…? How do you find S20 for the geometric series 4 + 12 + 36 + 108 + …? See all questions in Sums of Geometric Sequences Impact of this question 2168 views around the world You can reuse this answer Creative Commons License