Question

In an infinite G.P. the first term is A and the infinite sum 5, then A belongs to 

(a) A < –10 

(b) 0 < A < 10 

(c) 0 < A ≤ 10 

(d) None of these 

Answer 1

Correct option (b) 0 < A < 10

Explanation:

A/1-r = 5 then r = 1- A/5

Now since it is an infinite G.P. |r|<|, implies

–1 < 1 –A/5 < 1 or 0 < A < 10.