Question

If S = [1+(-1/3)][1+(-1/3)²][1+(-1/3)4][1+(-1/3)⁸....till n terms. Then S = ? 

(a) 4(10²ⁿ − 1) 

(b) 4/3(10ⁿ − 1) 

(c) 2/3(10ⁿ − 1) 

(d) None of these

Answer 1

Correct option (d) None of these   

Explanation: 

For n = 1 sum = 2/3

For n = 2 sum = 20/27

For n = 3 sum = 1640/2187

None of the options matches these numbers and hence option (d) is correct.