The sum of an infinite geometric series of real number is 14, and the sum of the cube of the terms of this series is 392 then the first term of the series is
-14
10
7
-5
As learnt in
Sum of infinite terms of a GP -
- wherein
first term
common ratio
Also if series is
Divide and
For
Option 1)
-14
This option is incorrect.
Option 2)
10
This option is incorrect.
Option 3)
7
This option is correct.
Option 4)
-5
This option is incorrect.