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    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!
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    (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}
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    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!
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    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!
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    (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.
 
 
 
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