Turn on thread page Beta
 You are Here: Home >< Maths

# Confusion watch

Announcements
1. Let .

How do you tell that ?

Thanks.
2. What's ?

Then show that
3. (Original post by notnek)
What's ?

Then show that

=
=

How do you show this is less than 0?

By the way, I think of other method, in which I attempt to show that, if , then . But I found it difficult to prove as well.
4. just a quick question.. which AS/A2 Level Module is this in?
5. Well for n > 3 the top is < 0, and the bottom is > 0.

Since u_n isn't defined for n=2,3 and u_n+1 isn't defined for n=1, I think you can reasonably assume n > 3 here.
6. (Original post by mfc20)
just a quick question.. which AS/A2 Level Module is this in?
This is stated at the solution of an AEA question, in which it states that without proof.

(Original post by DFranklin)
Well for n > 3 the top is < 0, and the bottom is > 0.

Since u_n isn't defined for n=2,3 and u_n+1 isn't defined for n=1, I think you can reasonably assume n > 3 here.
I'm really confused at those things, but can n be negative integers?

Thanks.
7. It can, if you defined the sequence for negative indices.
8. what you need to note is that as you get large n the denominator will increase faster than the numerator, so since n_x is going to be a certain number y the n_x+1 will be even smaller than n_x since it is a decreasing function.

don't you have to show that it gives integer solutions for n=something anyways?
9. (Original post by Civ-217)
I'm really confused at those things, but can n be negative integers?
A sequence is a function which has positive integers as its "input" (called the domain in C2), so cannot take negative integer values. In other words, the function, denoted by here is , and the input/domain is all the positive integers which make sense. Because the values and give division by zero, which we cannot have, we have to conclude that the sequence is not defined for those two values of .

Turn on thread page Beta
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: July 14, 2008
Today on TSR

Choose Respect

### University open days

• Manchester Metropolitan University
Wed, 14 Nov '18
• University of Chester
Wed, 14 Nov '18
• Anglia Ruskin University
Ambitious, driven, developing your career & employability? Aspiring in your field, up-skilling after a career break? Then our Postgrad Open Evening is for you. Postgraduate
Wed, 14 Nov '18
Poll
Useful resources

## Make your revision easier

### 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

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE