If sum of the series _ n=0 ^ r^n=S for |r|<1, then sum of the series _ n=0 ^ r^ 2n , is

JEE Main Mathematics question

If sum of the series for , then sum of the series , is

Answer: (D)

, so and . $

Create a free account to read the complete working, and practise questions like this in a timed test.

Question ID VK-021459