Results are out! Find what you need...fast. Get quick advice or join the chat
Hey! Sign in to get help with your study questionsNew here? Join for free to post

C2 Sequences

Announcements Posted on
Will you get the grades you need for uni? Get prepared today and de-stress, sign up to email alerts for course places! 02-06-2015
Waiting on IB results? Our IB results hub explains everything you need to know 01-06-2015
  1. Offline

    ReputationRep:
    I've got a sequences questions which I've done wrong/not sure how to do, and would be grateful for some help.

    1. The sequence u1, u2, u3, .... is defined by un = 2n^2
    a) Write down the value of u3.
    b) Express un+1 - un in terms of n, simplifying your answer.
    c) The differences between successive terms of the sequence form an arithmetic progression. For this aritmetic progression, state its first term and its common difference, and find the sum of its first 1000 terms.

    I've done a), and I got 18. I'm not sure about how I would do b), and for c) what does it mean by successive? So does it mean, u1, u2, u3, or is it alternate ones?

    Thanks
  2. Offline

    ReputationRep:
    U_{n+1} = 2(n+1)^2

    U_n = 2n^2


    Just take the latter from the former



    Successive juts means from one to the next
  3. Offline

    ReputationRep:
    (Original post by MedicalMayhem)
    I've got a sequences questions which I've done wrong/not sure how to do, and would be grateful for some help.

    1. The sequence u1, u2, u3, .... is defined by un = 2n^2
    a) Write down the value of u3.
    b) Express un+1 - un in terms of n, simplifying your answer.
    c) The differences between successive terms of the sequence form an arithmetic progression. For this aritmetic progression, state its first term and its common difference, and find the sum of its first 1000 terms.

    I've done a), and I got 18. I'm not sure about how I would do b), and for c) what does it mean by successive? So does it mean, u1, u2, u3, or is it alternate ones?

    Thanks
    Successive means in order, consecutive; not alternating. For b) it should be like TenOfThem said and you might have to expand the brackets but I'm not sure. For c) just find the first term and the common difference and the rest is just C1 knowledge.
  4. Offline

    ReputationRep:
    (Original post by TenOfThem)
    U_{n+1} = 2(n+1)^2

    U_n = 2n^2


    Just take the latter from the former



    Successive juts means from one to the next
    (Original post by uttamo)
    Successive means in order, consecutive; not alternating. For b) it should be like TenOfThem said and you might have to expand the brackets but I'm not sure. For c) just find the first term and the common difference and the rest is just C1 knowledge.
    Thanks I just got a bit confused :/

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. By joining you agree to our Ts and Cs, privacy policy and site rules

  2. Slide to join now Processing…

Updated: April 14, 2012
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.

New on TSR

Improving your uni offer

Why now is the time to think about Adjustment

Study resources
x

Think you'll be in clearing or adjustment?

Hear direct from unis that want to talk to you

Get email alerts for university course places that match your subjects and grades. Just let us know what you're studying.

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.