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Edexcel A2 C4 Mathematics June 2016 - Official Thread Watch

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    (Original post by 13 1 20 8 42)
    Yeah as it doesn't ask for what the maximum is or anything, just asks you to show that it doesn't "exceed" 5000. I guess that should imply an inequality
    Okay, thanks.
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    (Original post by imran_)
    are u the one that runs the physicsmaths tutor website
    No, his username is PhysicsMathsTut on here. I just used to like physics and maths. Now just mostly maths lol.
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    (Original post by NotNotBatman)
    If a population is modelled by  P= \frac{25}{5+20e^{-\frac{1}{3}t}} and you have to show that the population never exceeds 5000. (P is in thousands)

    But the mark scheme says award B0 for: as  t\rightarrow\infty, p\rightarrow \frac{25}{5}

    Unless you show that it is an increasing function, I don't want to take the long winded route for 1 mark, so how would I show the maximum value of P? As I don't really understand what's going on in the mark scheme.
    Which paper is this from?
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    (Original post by Zacken)
    180 over both of them.
    Ah, thank you. My teacher insisted that in the scenario where you got 89 on one of them and 91 on the other, you wouldn't get an A*.
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    (Original post by Turtlebunny)
    Ah, thank you. My teacher insisted that in the scenario where you got 89 on one of them and 91 on the other, you wouldn't get an A*.
    He's definitely wrong. I know of one user on here who got 85 on C3 and 100 on C4 and got his A*.
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    (Original post by Zacken)
    He's definitely wrong. I know of one user on here who got 85 on C3 and 100 on C4 and got his A*.
    Also, Zacken, I saw you did solutions for this year's C2 exam, will you be doing the same for C3 and C4?
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    (Original post by Turtlebunny)
    Also, Zacken, I saw you did solutions for this year's C2 exam, will you be doing the same for C3 and C4?
    I was going to but someone else is doing them instead. I'll be doing FP2 and FP3.
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    (Original post by Zacken)
    I was going to but someone else is doing them instead. I'll be doing FP2 and FP3.
    Ah, sweet. That'll be nice to have after FP2.
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    (Original post by Azzer11)
    Which paper is this from?
    January 2012, the last bit of question 8.
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    (Original post by Turtlebunny)
    Ah, thank you. My teacher insisted that in the scenario where you got 89 on one of them and 91 on the other, you wouldn't get an A*.
    I got 100 in C3 and 84 in C4 because C4 is icky. :bawling: but still got an A*
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    (Original post by SeanFM)
    I got 100 in C3 and 84 in C4 because C4 is icky. :bawling: but still got an A*
    I'm not a fan of C4 either Much prefer C3. Although, after doing loads of practice, my integration is getting up to scratch
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    (Original post by Turtlebunny)
    I'm not a fan of C4 either Much prefer C3. Although, after doing loads of practice, my integration is getting up to scratch
    Yes... just don't forget how to find the volume of a rotated solid or whatever (which is what I did and lost all the marks on that question )

    and vectors as well.. icky.. but draw diagrams, practice, and make sure you get as many marks as possible
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    (Original post by SeanFM)
    Yes... just don't forget how to find the volume of a rotated solid or whatever (which is what I did and lost all the marks on that question )

    and vectors as well.. icky.. but draw diagrams, practice, and make sure you get as many marks as possible
    Ah, yes, volumes of revolution Don't worry, I've got that on lockdown
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    quick question, if u can integrate functions via the reverse chain rule, why can't u integrate trigonometric functions by the reverse chain rule. For example : sin^2.
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    (Original post by BobAhmed)
    quick question, if u can integrate functions via the reverse chain rule, why can't u integrate trigonometric functions by the reverse chain rule. For example : sin^2.
    Well.. what is the integral of sin^2x if you try to use the reverse chain rule?
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    1/3 sin^3. 1/cosx?
    yh that doesn't work, but why?
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    (Original post by BobAhmed)
    1/3 sin^3. 1/cosx?
    yh that doesn't work, but why?
    Yeah... that's why I'm afraid I cannot offer an explanation

    However, a few things to note.

    If you have something icky in terms of trig that you need to integrate, you can use different formulae (eg factor formula, double angle formula, stuff in your formula bloklet) to change it into something that is easier to integrate, like coskx where k is a number - you know that the integral of that is 1/k * sinkx.

    Also, you can use the reverse chain rule or whatever to integrate things like
    sin^2x * cosx and 2x*e^(x^2) (latex doesn't like me :hide:)
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    (Original post by SeanFM)
    Yeah... that's why I'm afraid I cannot offer an explanation

    However, a few things to note.

    If you have something icky in terms of trig that you need to integrate, you can use different formulae (eg factor formula, double angle formula, stuff in your formula bloklet) to change it into something that is easier to integrate, like coskx where k is a number - you know that the integral of that is 1/k * sinkx.

    Also, you can use the reverse chain rule or whatever to integrate things like
    \sin^2 \theta + \cos^2 \theta=1

    ...latex in progress.
    yeah problem in original question is there is no derivative term to work with.
    So integral of sin^2xcosx is fine because we have the f'(x) term. Without it, we need alternative approaches
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    Is there a way to do latex automarically, looks cool formatted
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    latex??
 
 
 
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