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Edexcel A2 C4 Mathematics June 2016 - Official Thread Watch

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    (Original post by EnglishMuon)
    Maybe not specifically C4 related, but Im pretty sure the formulae you are referring to have been used a couple of times in some recent FP2 papers even though they aren't on the spec. One question I remember they basically tell you to use the formula and take you through it step by step, not even using any fp2 knowledge . Hopefully theyve made some better questions for this year.
    The same goes for partial fractions with x^2 + 9 on the bottom, for example. They are specifically ruled out in C4 but will be needed in FP2 or FP3 (I forget which, though probably FP3).
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    (Original post by tiny hobbit)
    I marked the applied papers upto 1992. There were 7 mechanics questions and one fiendish probability question. You were given the marks of your best 6 answers. If a candidate started with the probability question, you knew that it was because they were rubbish at mechanics and were going to do very badly on the paper.

    I've attached one of the papers for your entertainment - it was a bit of a struggle finding one whose filesize was small enough.
    Ooh, thank you for that! Were these a "general applied paper" or was it separated in "M1/M2/etc..." - I'm quite liking the look of Q6 and 7 on that paper, I might give them a go.

    What's with the lack of statistics, though?
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    (Original post by tiny hobbit)
    The same goes for partial fractions with x^2 + 9 on the bottom, for example. They are specifically ruled out in C4 but will be needed in FP2 or FP3 (I forget which, though probably FP3).
    lol I thought it was strange they suddenly disappeared when I was doing past papers last year Do you know why they keep removing little chunks of the syllabus? I mean I always hear people moaning about the course but didnt think that would persuade the exam boards to remove all but the easier stuff.
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    (Original post by Zacken)
    Yep! Nah, AFM isn't offered by IAL.



    Haha, thanks!
    Very impressive.

    Can I ask you from a physics graph question quickly, if I have a graph of F against v^2 from the equation - F=mv^2/r. Then how would you be able to gauge the shape of the graph, for constant radius. I would guess at a diagonal line passing through an origin rather than half of a quadratic curve but not too sure.

    Based on 3bii 1 from here - http://www.ocr.org.uk/Images/131309-...nian-world.pdf

    Thanks
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    (Original post by Mihael_Keehl)
    Very impressive.

    Can I ask you from a physics graph question quickly, if I have a graph of F against v^2 from the equation - F=mv^2/r. Then how would you be able to gauge the shape of the graph, for constant radius. I would guess at a diagonal line passing through an origin rather than half of a quadratic curve but not too sure.

    Based on 3bii 1 from here - http://www.ocr.org.uk/Images/131309-...nian-world.pdf

    Thanks
    Yes, it would be a straight line. Write y = F and x = v^2 then your equation is just y = mx for m = m/r. If you were plotting F against v then it would be half a quadratic.
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    (Original post by Mihael_Keehl)
    consider cos(3x-2x) - cos(3x+2x) = cos3xcos2x + sin3xsin2x
    - (cos3xcos2x - sin3xsin2x)
    = 2sin3xsin2x

    eg 2sin3xsin2x = cosx - cos5x

    You could do it by parts too.
    Hi, how did you know to pick cos(3x-2x) - cos(3x+2x) ?
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    (Original post by Zacken)
    Ooh, thank you for that! Were these a "general applied paper" or was it separated in "M1/M2/etc..." - I'm quite liking the look of Q6 and 7 on that paper, I might give them a go.

    What's with the lack of statistics, though?
    This was the syllabus before modules were invented. You did all of your exams at the end of the course, which is what Michael Gove has decided we should return to (he was the previous Education Secretary in the British Government).

    There was an alternative syllabus which was Pure and Statistics.
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    (Original post by Zacken)
    Ooh, thank you for that! Were these a "general applied paper" or was it separated in "M1/M2/etc..." - I'm quite liking the look of Q6 and 7 on that paper, I might give them a go.

    What's with the lack of statistics, though?
    (Original post by EnglishMuon)
    lol I thought it was strange they suddenly disappeared when I was doing past papers last year Do you know why they keep removing little chunks of the syllabus? I mean I always hear people moaning about the course but didnt think that would persuade the exam boards to remove all but the easier stuff.
    Apologies, the Factor formulae seem to have floated on and off the specification a few times. They get a mention in the specification starting in 2000:
    "The knowledge and use of identities such as 2 cos A cos B  cos (A + B) + cos (A – B) to solve equations and prove identities"

    They seem to have been finally dropped when the current C modules came in in 2004.

    Partial fractions with x^2 + 9 were in until 2000 then dropped.
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    (Original post by Zacken)
    Yes, it would be a straight line. Write y = F and x = v^2 then your equation is just y = mx for m = m/r. If you were plotting F against v then it would be half a quadratic.
    Thank you but is that because m/r is constant, constant gradient implying diagonal line etc.?

    (Original post by Glavien)
    Hi, how did you know to pick cos(3x-2x) - cos(3x+2x) ?
    Well I knew it would involve factor formulae, and so I saw that sin3xsin2x must cancel out, and we knew what we wanted to get.
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    (Original post by Mihael_Keehl)
    Thank you but is that because m/r is constant, constant gradient implying diagonal line etc.?
    Yep. We don't call it a diagonal line, by the way - we call it a straight line.
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    (Original post by Zacken)
    Yep. We don't call it a diagonal line, by the way - we call it a straight line.
    Thank you this makes more sense, and yes haha.
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    (Original post by Mihael_Keehl)
    Thank you this makes more sense, and yes haha.
    No problem.
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    (Original post by Zacken)
    The one on the abnormally easy paper?
    Spoiler:
    Show
    2010
    nah not that recent
    Spoiler:
    Show
    the grand unveil, I 2009
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    (Original post by DylanJ42)
    nah not that recent
    Spoiler:
    Show
    the grand unveil, I 2009
    Oh. :lol: Look at the one I mentioned though, it's even more focused around the technique. :eek:
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    (Original post by Zacken)
    Oh. :lol: Look at the one I mentioned though, it's even more focused around the technique. :eek:
    oh yea that paper was my most recent mock ,how didnt i remember that question :facepalm: i was so paranoid during the exam thinking "20 marks for this...:eek: " I thought i was missing something but apparently not :laugh:

    question 1 was a little too straightforward as well (even though i missed it up at the end ), easy paper i agree
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    (Original post by DylanJ42)
    oh yea that paper was my most recent mock ,how didnt i remember that question :facepalm: i was so paranoid during the exam thinking "20 marks for this...:eek: " I thought i was missing something but apparently not :laugh:

    question 1 was a little too straightforward as well (even though i missed it up at the end ), easy paper i agree
    Yeah, you know it's easy when it's a 103 for an S. :rofl:
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    (Original post by Zacken)
    Yeah, you know it's easy when it's a 103 for an S. :rofl:
    i usually have a look at boundaries before I start just to have an idea of how many solutions ill need, so they shocked me a little. But once I started I understood why, I can never usually attempt 6 due to either time constraints/being dumb it was nice to have 6 questions to mark for once. :laugh: How did you do in it?
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    Hi Zacken + others. - I hope your Easter holiday is going well.

    I was just wondering whether any of you know if we need to learn the Var(x)/E(x) proofs for Uniform distribution- S2? It's just I've seen it being mentioned in a few online resources but then not in others so I'm unsure + don't want to waste memory space/time if it isn't required tbh.

    Thanks in advance.
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    (Original post by Anon_98)
    Hi Zacken + others. - I hope your Easter holiday is going well.

    I was just wondering whether any of you know if we need to learn the Var(x)/E(x) proofs for Uniform distribution- S2? It's just I've seen it being mentioned in a few online resources but then not in others so I'm unsure + don't want to waste memory space/time if it isn't required tbh.

    Thanks in advance.
    Hey! Hope yours is as well.

    Bad news: well, I've seen it pop up in a past paper once.

    Good news: You don't need to remember it. It's essentially all in your formula book.

    Can you see the bit in the "PDF is \frac{1}{b-a}" thing? And then above that table is "Expectation/mean is \int xf(x) \, \mathrm{d}x" and the corresponding thing for \text{Var}(x)?

    So all you need to do is, if you're asked to prove it, you don't need to remember anything. Open your formula booklet, they tell you the pdf is f(x) = \frac{1}{b-a}, they want you to find the E(X), okay then, just plug it into the formula given:

    \displaystyle E(X) = \int xf(x) \, \mathrm{d}x = \int_a^b \frac{x}{b-a} \, \mathrm{d}x = \frac{1}{a-b} \int_a^b x \, \mathrm{d}x which you can finish up from here.

    And they want variance, okay then, still just plugging in:

    \displaystyle \text{Var}(X) = \int x^2 f(x) \, \mathrm{d}x - \mu^2 = \int_a^b \frac{x^2}{b-a} \, \mathrm{d}x - \mu^2 = \frac{1}{b-a} \int_a^b x^2 \, \mathrm{d}x - \mu^2

    Where \mu is just the expectation you found above.

    For the expectation:
    Spoiler:
    Show
    \displaystyle \int_a^b x \, \mathrm{d}x = \bigg[\frac{x^2}{2}\bigg]_a^b = \frac{b^2 - a^2}{2}

    So \displaystyle E(X) = \frac{1}{2} \times (b^2 - a^2) \times \frac{1}{b-a} = \frac{(b-a)(b+a)}{2(b-a)}
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    (Original post by Zacken)
    No problem.
    Can I ask what the standard of the papers were like, were any of them particularly difficult.

    (Original post by Anon_98)
    Hi Zacken + others. - I hope your Easter holiday is going well.

    I was just wondering whether any of you know if we need to learn the Var(x)/E(x) proofs for Uniform distribution- S2? It's just I've seen it being mentioned in a few online resources but then not in others so I'm unsure + don't want to waste memory space/time if it isn't required tbh.

    Thanks in advance.
    The E(X) is simple, so maybe but I doubt it.

    The Var (X) would take too long and I think it is mentioned in one of the guides that this proof is not necessary in the s2 exinmation maybe someone else can confirm.

    Just learn them anyway, not too difficult
 
 
 
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