Can you tell me why the sum of geometric series of -3+15-75+375...,n=8 a positive number, not negative?
2 Answers
Jul 8, 2017
See below:
Explanation:
Let's look at the series this way:
We have 8 numbers. They start with
If I add up each group of 2 numbers, I'll get a positive number:
And clearly if I add these 4 numbers up, I'll get a positive number.
Jul 8, 2017
The given GP has 1st term
We know the sum of the series up to n th term is
Here