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    (Original post by manlikem)
    thanks! because on the mark scheme it says that I have to make sinx= u. But I in an exam I would have made cosx = u so I was confused. Does it matter which value you make u ?
    Well you can do it using that method but that makes less sense; in their case, they presumably want you to write, using their substitution:

    \displaystyle\int \cos^3(x)\sin(x) \ dx = \displaystyle\int (\cos^2(x)\sin(x))\cos(x) \ dx = \displaystyle\int (1 - u^2)u \ du

    Which just seems like more work, albeit not a whole lot more.
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    (Original post by frozo123)
    omg I'm freaking out I can't integrate
    so if there's a coefficient in a trig function you keep it
    but if the angle is say k
    you do 1/k times the coefficient and integration of the trig function right?

    so is the answer
    y=2(e^3tanx-3 ) ?
    Don't worry, it's a lot easier than you think; 3 is just a constant - forget about it somewhat. It is simply a multiplication factor of the RHS integral. The only real calculations you need to worry about are:

    \displaystyle\int y \ dy and \displaystyle\int \sec^2(x) dx

    If there is a coefficient to the angle variable then there is going to be some change, yes. But in this case there is nothing like that. The answer is not the one you have given.
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    (Original post by Paraphilos)
    Don't worry, it's a lot easier than you think; 3 is just a constant - forget about it somewhat. It is simply a multiplication factor of the RHS integral. The only real calculations you need to worry about are:

    \displaystyle\int y \ dy and \displaystyle\int \sec^2(x) dx

    If there is a coefficient to the angle variable then there is going to be some change, yes. But in this case there is nothing like that. The answer is not the one you have given.
    Oh it's y not 1/y ..
    wow I'm so ****ed
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    I really don't know what to do - done papers and the sort but feel as though i should actually be doing some work the night before the exam rather than wasting time on TSR. Any suggestions?
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    (Original post by Gilo98)
    I really don't know what to do - done papers and the sort but feel as though i should actually be doing some work the night before the exam rather than wasting time on TSR. Any suggestions?
    Look over some small parts that you find difficult and then take your night off and watch a film or something. If you have done all the past papers, you have probably done enough.
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    (Original post by Gilo98)
    I really don't know what to do - done papers and the sort but feel as though i should actually be doing some work the night before the exam rather than wasting time on TSR. Any suggestions?
    Im doing both. But last night i was revising geography, and being on here helped as i was talking and revising to people on a live chat. i know mtahs is different from geography, but i felt more confident and relaxed doing it!!
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    can someone help on 4b how do i know what trig identity to use for the cartesian equation ???? https://5a302d29ff432793ce79475dd3db...%20Edexcel.pdf
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    (Original post by Paraphilos)
    Look over some small parts that you find difficult and then take your night off and watch a film or something. If you have done all the past papers, you have probably done enough.
    did a past paper earlier though and silly errors keep stopping me from getting full ums - might just have to call it a day and pray to the edexcel gods
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    Thats true tbh - strength in numbers if we collectively **** ourselves theres a strength in it
    (Original post by Alice Moody)
    Im doing both. But last night i was revising geography, and being on here helped as i was talking and revising to people on a live chat. i know mtahs is different from geography, but i felt more confident and relaxed doing it!!
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    (Original post by Gilo98)
    I really don't know what to do - done papers and the sort but feel as though i should actually be doing some work the night before the exam rather than wasting time on TSR. Any suggestions?
    do some gold papers? maybe have a looke at a replacement or withdrawn paper? IYGB? solomon?
    tbh, you should get an early nights sleep, but I reckon you can still do one more paper or maybe 2 before sleeping early....
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    (Original post by Maham88)
    can someone help on 4b how do i know what trig identity to use for the cartesian equation ???? https://5a302d29ff432793ce79475dd3db...%20Edexcel.pdf
    Note that 1 - 2\sin^2(\alpha) \equiv \cos(2\alpha)

    Does this help?
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    (Original post by Alice Moody)
    You cant do it by parts, as i keep going in loops and circles haha. I think you do it by inspection? which is something i cant do, but will have another try
    Obviously you can't do it by parts, straight away you can see that it won't work this way
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    (Original post by Jamborambowambo)
    Does anyone know when you put the modulus bars wrapped around a function in- is it just when you integrate? And whether or not you can lose marks for putting in brackets instead?

    Someone answer this, more interested in the whether you lose marks part, cheers.
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    What does everyone need to get an A approximately?
    or are you all looking at A*s?
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    (Original post by Paraphilos)
    Note that 1 - 2\sin^2(\alpha) \equiv \cos(2\alpha)

    Does this help?
    ohh okay yeah. its just i don't know when to use what trig identity
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    Ah.. when you find a improper fraction for partial fractions... do you divide by it first? or can you just express the letter "A" on it's own first and work it out from there?
    Hope this makes sense LOL
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    (Original post by DomRauba)
    Someone answer this, more interested in the whether you lose marks part, cheers.
    Would also like to know this!
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    (Original post by Bustamove)
    do some gold papers? maybe have a looke at a replacement or withdrawn paper? IYGB? solomon?
    tbh, you should get an early nights sleep, but I reckon you can still do one more paper or maybe 2 before sleeping early....
    I think that is what i shall do - i have a history exam tomorrow AM so after dinner in 5 min I'll casually do a 'difficult' paper, brush over some history notes then get to bed early. I seem to go nocturnal on study leave it's so annoying
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    (Original post by anonwinner)
    Obviously you can't do it by parts, straight away you can see that it won't work this way
    AHAHAH!! im not smart enough to see that though haha
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    (Original post by frozo123)
    What does everyone need to get an A approximately?
    or are you all looking at A*s?
    After C3, chances of me getting A* is slim to zero... so I'll probably be aiming as high an A as I can get overall... Hopefully university will give me some leeway for having a high ums score overall for maths rather than an A*...
 
 
 
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