You are Here: Home >< Maths

# Difference equation watch

1. where

i get as the solution which should be -½ not -2

but what is because that's what i kinda guess my answer off i got -4 and 8 which of course is wrong so can someone point me in the right direction?
2. (Original post by will'o'wisp2)

where

i get as the solution which should be -½ not -2

but what is because that's what i kinda guess my answer off i got -4 and 8 which of course is wrong so can someone point me in the right direction?
You can rewrite your relation as by mapping (ie increasing each subscript by 1) and rearranging for

So and - two conditions which are not satisfied by your solution.
3. (Original post by RDKGames)
You can rewrite your relation as by mapping (ie increasing each subscript by 1) and rearranging for

So and - two conditions which are not satisfied by your solution.
ah coolio, that's another thing then i need to note down

thanks a bunch
4. (Original post by will'o'wisp2)
ah coolio, that's another thing then i need to note down

thanks a bunch
No problem, also I meant to say that then, and with . Then proceed to find your solution, but instead of write as we increased them by 1. Then reduce the subscripts by 1 to their original state after you achieve it, as then the context of the question and conditions are satisfied.

You can skip all of this increasing/decreasing if you just let to begin with in your Q and work in k's before you convert back to n's

### 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: October 10, 2017
Today on TSR

### Edexcel C2 Core Unofficial Markscheme!

Find out how you've done here

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