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

    12
    ReputationRep:
    I have been struggling with this question. I do know how to do inverse function but I think the x>3 throws me off. I got up to 0=x^2>1 which seems very wrong.Name:  A.jpg
Views: 13
Size:  21.1 KB
    • Community Assistant
    Offline

    11
    ReputationRep:
    (Original post by MainlyMathsHelp)
    I have been struggling with this question. I do know how to do inverse function but I think the x>3 throws me off. I got up to 0=x^2>1 which seems very wrong.Name:  A.jpg
Views: 13
Size:  21.1 KB
    Find g inverse and set equal to f. Then solve for x and it should become clear why the x>3 is relevant.
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by SherlockHolmes)
    Find g inverse and set equal to f. Then solve for x and it should become clear why the x>3 is relevant.
    I did that and got 0 = 2x^2 - 20. I tried substituting x >3 into x and that got me to 0=2x^2 > 18 - 20 which got me to 0 = x^2 > -1
    • Community Assistant
    Offline

    11
    ReputationRep:
    (Original post by MainlyMathsHelp)
    I did that and got 0 = 2x^2 - 20. I tried substituting x >3 into x and that got me to 0=2x^2 > 18 - 20 which got me to 0 = x^2 > -1
    Therefore:

    x^2 - 10 = 0

    Now use difference of two squares.
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by SherlockHolmes)
    Therefore:

    x^2 - 10 = 0

    Now use difference of two squares.
    Oh of course. I went down the route of substituting x with x>3 which meant I got lost. The exact value of x is root 10. Thank you!
 
 
 
  • 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
    What newspaper do you read/prefer?
    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.