Evaluate this geometric series:

Question

7 + 14 + 28 + ... + 3584

Answer 1

S = 7 + 14 + 28 + ... + 3584

2 S = 2 (7 + 14 + 28 + ...1792 + 3584) =

2*7 + 2*14 + +...+ 2* 1792 + 2*3584 =

14 + 28 + ...+ 3584 + 7168 =

S - 7 + 7168 = S + 7161

2S = S + 7161 --------->

S = 7161