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

    8
    ReputationRep:
    Hi everyone,

    I've been having some trouble on this C3 Quadratics Question (Image of Qu is attached).

    For part a) I have found that the curve crosses the x-axis at (0,0) and (4a,0) but when it comes to sketching the graph, the mark scheme seems to have reflected all x values > 0 in the y-axis. I have attached an image of the mark scheme for clarification but can someone explain the graph sketch for part a)?

    Thanks!
    Attached Images
      
    • Community Assistant
    • Welcome Squad
    Offline

    20
    ReputationRep:
    (Original post by DhylanP - CRGS)
    Hi everyone,

    I've been having some trouble on this C3 Quadratics Question (Image of Qu is attached).

    For part a) I have found that the curve crosses the x-axis at (0,0) and (4a,0) but when it comes to sketching the graph, the mark scheme seems to have reflected all x values > 0 in the y-axis. I have attached an image of the mark scheme for clarification but can someone explain the graph sketch for part a)?

    Thanks!
    It's an even function, which has the property f(-x)=f(x) and graphically it means that a function is symmetrical in the line x=0 (which is the y-axis). Since you can draw f(x) for x>0, you just need to reflect this portion in the line y=0 to get the complete graph on \mathbb{R}
    Offline

    17
    ReputationRep:
    As it is an even function it is symmetrical about the y axis
    (Original post by DhylanP - CRGS)
    Hi everyone,

    I've been having some trouble on this C3 Quadratics Question (Image of Qu is attached).

    For part a) I have found that the curve crosses the x-axis at (0,0) and (4a,0) but when it comes to sketching the graph, the mark scheme seems to have reflected all x values > 0 in the y-axis. I have attached an image of the mark scheme for clarification but can someone explain the graph sketch for part a)?

    Thanks!
    Posted on the TSR App. Download from Apple or Google Play
    • Thread Starter
    Offline

    8
    ReputationRep:
    Hi guys,

    Thanks for your responses. Can you explain why an even function means that you reflect it in the y-axis or do you just need to learn that?

    Thanks!
    • Community Assistant
    • Welcome Squad
    Offline

    20
    ReputationRep:
    (Original post by DhylanP - CRGS)
    Hi guys,

    Thanks for your responses. Can you explain why an even function means that you reflect it in the y-axis or do you just need to learn that?

    Thanks!
    That's just the definition of an even function, f(-x)=f(x), which you need to learn.

    Think about what the above actually means graphically and how you get symmetry around x=0 from it.
 
 
 
  • 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.