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

    1
    ReputationRep:
    (x2)-3x+1=0 with roots a and b

    show that a4 +b4= (a2 +b2)^2 - 2(ab)^2 having trouble with this proof can anyone help me with this
    Offline

    12
    ReputationRep:
    X=3+/- root5 all over 2 using completing the square or quadratic formula then sub in to equation and both sides should be equal? Not sure though


    Posted from TSR Mobile
    Offline

    12
    ReputationRep:
    The other answer seems far more complicated so I'm gonna assume mine was wrong


    Posted from TSR Mobile
    Offline

    15
    ReputationRep:
    Just expand the RHS, it's an identity. So just expand  (a^2+b^2)^2 -2(ab)^2 .
    Offline

    15
    ReputationRep:
    (Original post by Foreverton)
    The other answer seems far more complicated so I'm gonna assume mine was wrong


    Posted from TSR Mobile
    No, it's a different technique but it wasn't really suited to this problem I felt.
    • Thread Starter
    Offline

    1
    ReputationRep:
    cheers i see it now
    (Original post by B_9710)
    Just expand the RHS, it's an identity. So just expand  (a^2+b^2)^2 -2(ab)^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
    Would you like to hibernate through the winter months?
    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.