You are Here: Home >< Maths

# Geometric Series watch

1. Hey I need help on this question:

I'm not sure how to go about this question. I only want help for the first part up to the word hence. Thanks in advance
2. (Original post by MathStudent1994)
Hey I need help on this question:

I'm not sure how to go about this question. I only want help for the first part up to the word hence. Thanks in advance
So write down the geometric sum term by term (you should recognise it) and then differentiate it term by term. Now find the sum to infinity of the geometric series. What might happen if you differentiate that?
3. (Original post by Mr M)
So write down the geometric sum term by term (you should recognise it) and then differentiate it term by term. Now find the sum to infinity of the geometric series. What might happen if you differentiate that?

Got it! Thanks, seems fairly obvious now
4. (Original post by MathStudent1994)
Got it! Thanks, seems fairly obvious now
Good!

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 1, 2013
The home of Results and Clearing

### 2,657

people online now

### 1,567,000

students helped last year
Today on TSR

### University open days

1. Sheffield Hallam University
Tue, 21 Aug '18
2. Bournemouth University
Wed, 22 Aug '18
3. University of Buckingham
Thu, 23 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams