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Edexcel Core 3 - 21st June 2016 AM Watch

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    (Original post by Zacken)
    There's no specific amount of work that I can tell you to do; you'll need to decide on that yourself but it's certainly very doable, you're basically already there you just need a smidge more practice and understanding. It's time to really drill down on your weaknesses and analyse your performances on past papers in depth. What topics do you frequently lose marks on? Isolate that topic and work on it thoroughly then rinse and repeat for each topic. You have plenty of time, you can do this, easily.
    Thanks a lot for the encouragement, I had a class test on C3 today and it didn't go well, so annoying as over Easter I was really getting the hang of it and this has knocked my confidence. On the other it was definitely a hard paper as everyone found it hard


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    (Original post by Don Joiner)
    Thanks a lot for the encouragement, I had a class test on C3 today and it didn't go well, so annoying as over Easter I was really getting the hang of it and this has knocked my confidence. On the other it was definitely a hard paper as everyone found it hard


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    No worries - the most important thing is that you learn something from it (like what you need to work on).
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    Can someone please post some difficult domain/range questions please.


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    For question 8 (c) from the January 2014 (IAL) paper, why can you equate the f(x) function to the f(t) function? How are they related in any way?

    Also, with the answer k = 9/8, the equation f(t) = 9/8e^t does not have a solution as it does not cross the x-axis. So, how come the question says there is one real solution?
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    (Original post by Glavien)
    For question 8 (c) from the January 2014 (IAL) paper, why can you equate the f(x) function to the f(t) function? How are they related in any way?

    Also, with the answer k = 9/8, the equation f(t) = 9/8e^t does not have a solution as it does not cross the x-axis. So, how come the question says there is one real solution?
    You're not equating the f(x) function to the f(t) function, remember that all the letter inside the bracket of the function is a dummy variable; i.e: if I say f(x) = 2x, then the only use of the x in the bracket is to tell me that the x's are the variables. But I might as well just say f(t) = 2x.

    So, if you have f(x) = 3 - 2e^(-x) then I can say that f(t) = 3 - 2e^(-t), it makes no difference, the letter is only there to tell me that the t or the x is what changes and everything else is constant.

    Now, the equation f(t) = 9/8e^t does have a solution; precisely when f(t) intersects 9/8e^t.
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    (Original post by Zacken)
    You're not equating the f(x) function to the f(t) function, remember that all the letter inside the bracket of the function is a dummy variable; i.e: if I say f(x) = 2x, then the only use of the x in the bracket is to tell me that the x's are the variables. But I might as well just say f(t) = 2x.

    So, if you have f(x) = 3 - 2e^(-x) then I can say that f(t) = 3 - 2e^(-t), it makes no difference, the letter is only there to tell me that the t or the x is what changes and everything else is constant.

    Now, the equation f(t) = 9/8e^t does have a solution; precisely when f(t) intersects 9/8e^t.
    Ohh, I think I got it. So your just finding the value of k when the two graphs intersect, right?
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    (Original post by Glavien)
    Ohh, I think I got it. So your just finding the value of k when the two graphs intersect, right?
    Yep, pretty much.
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    (Original post by Zacken)
    Yep, pretty much.
    Thanks, as always
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    For questions like 'Express 2cosx + 5sinx in the form R cos (x − α), where R > 0 and 0 < α < π/2', will we always be given the form to write the expression in, like in this question? Is there an easy way to know how you could express 2cosx + 5sinx without the form given in the question? Thanks in advance!
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    (Original post by Glavien)
    For questions like 'Express 2cosx + 5sinx in the form R cos (x − α), where R > 0 and 0 < α < π/2', will we always be given the form to write the expression in, like in this question? Is there an easy way to know how you could express 2cosx + 5sinx without the form given in the question? Thanks in advance!
    You will always be given the form in the question. But otherwise, if you see something of the form a\cos x + b\sin x it's representable in the form R\cos (x-\alpha) or R\sin(x-\alpha) always and it doesn't really matter which one you pick since they're just translations of each other.
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    (Original post by Glavien)
    For questions like 'Express 2cosx + 5sinx in the form R cos (x − α), where R > 0 and 0 < α < π/2', will we always be given the form to write the expression in, like in this question? Is there an easy way to know how you could express 2cosx + 5sinx without the form given in the question? Thanks in advance!
    I think the form that it's supposed to be in already is easy enough?


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    Need help for range and domain questions. Always get them wrong on the paper. Anyone know how to attempt those type questions?

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    Eh really need to start revising C3.
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    (Original post by arks_007)
    Need help for range and domain questions. Always get them wrong on the paper. Anyone know how to attempt those type questions?

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    For which type of functions, fractional, trigonometric, exponential...?
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    (Original post by arks_007)
    Need help for range and domain questions. Always get them wrong on the paper. Anyone know how to attempt those type questions?
    I've written two, very detailed, posts over the past year or so that explains domains and ranges - if you could just take a few minutes to sit down and read them, it'll be worth your while (hopefully).

    Post 1 and Post 2.
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    (Original post by Zacken)
    I've written two, very detailed, posts over the past year or so that explains domains and ranges - if you could just take a few minutes to sit down and read them, it'll be worth your while (hopefully).

    Post 1 and Post 2.
    Wow those posts are very helpful
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    (Original post by Zacken)
    I've written two, very detailed, posts over the past year or so that explains domains and ranges - if you could just take a few minutes to sit down and read them, it'll be worth your while (hopefully).

    Post 1 and Post 2.
    thank you very much zacken. very helpful!!!thank you very much zacken. very helpful!!!
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    (Original post by SaadKaleem)
    Eh really need to start revising C3.
    Don't we all ha
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    (Original post by SaadKaleem)
    Wow those posts are very helpful
    (Original post by arks_007)
    thank you very much zacken. very helpful!!!thank you very much zacken. very helpful!!!
    Thanks guys.
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    https://a086a5a2f39bda93734c56a63fab...%20Edexcel.pdf

    hi for question 4b i need help for the range. So far ive subbed 0 into it to get g(x)<= 3

    but i dont understand how the other value is calculated
 
 
 
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