Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    5
    ReputationRep:
    The sequence u1,u2,u3 is defined by the recurrence relation
    Un+1 = (un)^2 -1 N>1
    A) find expressions for u2 and u3 in terms of k
    Given also that u2 + u3=11
    B) find the possible values of k
    Offline

    17
    ReputationRep:
    (Original post by Katiekat2000)
    The sequence u1,u2,u3 is defined by the recurrence relation
    Un+1 = (un)^2 -1 N>1
    A) find expressions for u2 and u3 in terms of k
    Given also that u2 + u3=11
    B) find the possible values of k
    are you given an initial value for U1 in terms of k? or do they want you to let U1 = k?
    • Political Ambassador
    Offline

    3
    ReputationRep:
    I'm assuming you've been given u_1 in terms of k ?

    If so then you just have to use the recurrence relation

    u_2 = u_{1+1} = (u_1)^2 - 1

    etc.

    And for part b use that information to form an equation.
    • Thread Starter
    Offline

    5
    ReputationRep:
    (Original post by DylanJ42)
    are you given an initial value for U1 in terms of k? or do they want you to let U1 = k?
    U1 = k
    Offline

    17
    ReputationRep:
    (Original post by Katiekat2000)
    U1 = k
    okay so if  U_{n+1} = (U_n)^2 - 1 then

     \displaystyle U_{2} = (U_1)^2 - 1

    and  \displaystyle U_{3} = (U_2)^2 - 1

    can you try sub in  \displaystyle U_1 = k into the first of those two and see what you get for  \displaystyle U_2
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Did TEF Bronze Award affect your UCAS choices?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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

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