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Edexcel A2 C4 Mathematics June 2016 - Official Thread Watch

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    (Original post by SaadKaleem)
    Can easily be done with observation, sub in the x parameter equation, a very small value of t, say 0.01 (because 0 isn't included in the parameter domain) and observe what happens to x. You'll get a very large value of x.

    Sub t=pi/2 in the x parametric equation, you'll get x=0.

    Therefore the domain is x >= 0

    You could also plot the cartesian graph, to observe.
    thanks
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    (Original post by sabahshahed294)
    https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf

    In Q3a, when we are differentiating implicity, the combined x and y part(4xy in this case), what do we tend to do first? (Stupid question Ik, but I get stuck in this part ALL the time since I get confused and idk why though ). A minor explanation or working would be helpful. TIA!
    You need to use the product rule, carefully with brackets because the negative sign multiplies with all the terms.

    Whenever you'll differentiate a "y" term, you'll have to put dy/dx infront of it, because you're actually differentiating with respect to x.

    The reason behind this is, For example: It's as if the "dy's" cancel each other out.
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    (Original post by michael242103)
    thanks
    No Problem. Feel free to tag me, if you're stuck in anything else.
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    (Original post by SaadKaleem)
    You need to use the product rule, carefully with brackets because the negative sign multiplies with all the terms.

    Whenever you'll differentiate a y term, you'll have to put dy/dx infront of it, because you're actually differentiating with respect to x.

    Okay so it goes like this! So, we would differentiate this wrt to y as well in the next step right? (I mean the d/dy(9y) )
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    (Original post by sabahshahed294)
    Okay so it goes like this! So, we would differentiate this wrt to y as well in the next step right? (I mean the d/dy(9y) )
    Obviously to differentiate y, you'll have to differentiate with respect to y, but to make it "equivalent" you have to put dy/dx sign infront of it, as if they cancel. I've explained above.

    Further on to differentiate, about the expression you're talking about:

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    (Original post by SaadKaleem)
    Obviously to differentiate y, you'll have to differentiate with respect to y, but to make it "equivalent" you have to put dy/dx sign infront of it, as if they cancel. I've explained above.

    Further on to differentiate, about the expression you're talking about:

    I think I'm getting it now. Thanks. This will help me out now!
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    (Original post by sabahshahed294)
    I think I'm getting it now. Thanks. This will help me out now!
    Read my 1st post above again, edited it (if you haven't already), maybe you'll understand more clearly.
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    (Original post by SaadKaleem)
    Read my 1st post above again, edited it (if you haven't already), maybe you'll understand more clearly.
    Yeah I read. I just get confused in this part easily but I think a bit of practice now it'll be okay.(I hope )
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    Can someone explain why these angles are the same?Name:  Screen Shot 2016-06-16 at 22.31.12.png
Views: 100
Size:  38.9 KB
    Thnks
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    https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf

    For q7 part B
    I rearranged it into tan(2theta +20)
    but the mark scheme rearranged it into tan(2theta+10)

    what am i doing wrong.

    MS: https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf
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    (Original post by Louiseelg0rt)
    Can someone explain why these angles are the same?Name:  Screen Shot 2016-06-16 at 22.31.12.png
Views: 100
Size:  38.9 KB
    Thnks
    Isn't that from the IAL paper? that trig application question?
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    (Original post by Lilly1234567890)
    https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf

    For q7 part B
    I rearranged it into tan(2theta +20)
    but the mark scheme rearranged it into tan(2theta+10)

    what am i doing wrong.

    MS: https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf
    Compare the expressions for the cos or sin angles, Cos is much easier in this case. The first is x+30, the 2nd one is 2theta + 40.

    so if you put 2theta + 10 into x, you'll get the expression 2theta + 40.

    That's the reason, x= 2theta + 10.
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    (Original post by sabahshahed294)
    Yeah I read. I just get confused in this part easily but I think a bit of practice now it'll be okay.(I hope )
    It's quite easy stuff, shouldn't be "hard" once you've practiced a bit.
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    Can somebody who finds the rates questions really easy tell me what they did in terms of practise? Ive done a fair bit of these questions but still find im not as comfortable doing them as say an integration question - getting pretty frustrated. Perhaps I'm not approaching them the right way?
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    (Original post by lordoftheties)
    Can somebody who finds the rates questions really easy tell me what they did in terms of practise? Ive done a fair bit of these questions but still find im not as comfortable doing them as say an integration question - getting pretty frustrated. Perhaps I'm not approaching them the right way?
    Post a question for example and I'll be able to help. :hugs:

    Generally, I'd try to draw a shape of the object & from there figure out what units of the value they've given for example, say they've given 120 cms^-1 <--- I know straight away thats dx/dt from the units and then write something along like
    dx/dt ---> dx/dv . dv/dt.

    Post a example where its involved as a integration question as I can't recall how they are if they are put in a integration context as generally they are by themselves as a separate question but I should still be able to help.
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    Crash course of vectors!
    https://www.youtube.com/watch?v=4RglgO93VfM

    A little might be missed out but enough to get started on Past papers!
    (Original post by кяя)
    Thanks for your quick replies!
    What would you suggest for an effective revision schedule? I have C3, C4 and S2 but C3 is done I just need practice papers now. I was thinking:

    1. Textbook/Exam Solutions
    2. Past papers
    3. Solomon Papers
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    (Original post by ryandaniels2015)
    Crash course of vectors!
    https://www.youtube.com/watch?v=4RglgO93VfM

    A little might be missed out but enough to get started on Past papers!
    What's left out?
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    How do you get from 8^(1/6) to root2??


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    (Original post by Glavien)
    How do you get from 8^(1/6) to root2??


    Posted from TSR Mobile
    duh.
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    (Original post by lordoftheties)
    Can somebody who finds the rates questions really easy tell me what they did in terms of practise? Ive done a fair bit of these questions but still find im not as comfortable doing them as say an integration question - getting pretty frustrated. Perhaps I'm not approaching them the right way?
    Connected rates of change are often similar types of question. Ideas include:
    Think what the 3 differentials in your equation must be
    Use units from the question to help you
    Think what basic shape info you need to create your missing differential

    Please put up a question you don't like for us to look at
 
 
 
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