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# C3 - Quadratics Help. watch

1. 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

2. (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 and graphically it means that a function is symmetrical in the line (which is the y-axis). Since you can draw for , you just need to reflect this portion in the line to get the complete graph on
3. 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!
4. 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!
5. (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, , which you need to learn.

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

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