You are Here: Home >< Maths

# C1 Sequences and Series Question NEED HELP watch

1. Okay so I know how to do these (sorta, I was off in the lesson and I've caught up but I'm still not entirely sure!) A question they did in the lesson was:

1) The sequence u1 u2 u3 is defined by the recurrence relation
un+1=(-1)^n Un+d
where d is constant u1=2

a)Show that U5=2
b)Deduce an expression for u10 in terms of d
c) Given that U3=3U2, find the value of d

I have a lesson tomorrow so I could really do with getting this answered as soon as possible!
2. Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.

Just quoting in Fox Corner so she can move the thread if needed
Spoiler:
Show
(Original post by Fox Corner)
x
3. For part a you have to go through the sequence. U2=(-1)^2U1+d=d+2
U3= (-1)^3[d+2]+d=-2 etc etc and U5 turns out to be 2 because of the way that all the ds cancel.

By looking at the pattern of ds and 2 in the terms you have found you can deduce what U10 is.

for part c you have U3 and U2 from part a and so can set up the equ and solve for d

### 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: November 2, 2016
The home of Results and Clearing

### 1,941

people online now

### 1,567,000

students helped last year
Today on TSR

Hang on, have Edexcel's come out already?

### University open days

1. Bournemouth University
Fri, 17 Aug '18
2. University of Bolton
Fri, 17 Aug '18
3. Bishop Grosseteste University
Fri, 17 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