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    (Original post by Slice'N'Dice)
    Yeah, what does these bits refer to though?
    x0 is simply the number 2.4, which they give you.

    To get x1 you put 2.4 into the formula

    To get x2 you put x1 into the formula

    To get x3 you put x2 into the formula

    So....

    x1 = 4 - ln2(2.4) = 4 - ln4.8 = 2.431384082

    x2 = 4 - ln2(2.431384082) = 2.418392143

    x3 = 4 - ln2(2.418392143) = 2.423749904

    Tip - Type x0 into your calculator, press "=", then use the "Ans" button to type a general formula. Then just keep pressing "="

    e.g. 4 - ln2Ans
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    (Original post by seankhn)
    x0 is simply the number 2.4, which they give you.

    To get x1 you put 2.4 into the formula

    To get x2 you put x1 into the formula

    To get x3 you put x2 into the formula

    So....

    x1 = 4 - ln2(2.4) = 4 - ln4.8 = 2.431384082

    x2 = 4 - ln2(2.431384082) = 2.418392143

    x3 = 4 - ln2(2.418392143) = 2.423749904

    Tip - Type x0 into your calculator, press "=", then use the "Ans" button to type a general formula. Then just keep pressing "="

    e.g. 4 - ln2Ans
    Oh! I get it now!

    Many thanks seankhn.
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    Given that p=secθ-tanθ and q=secθ+tanθ show that p=1/q

    Pretty sure I did this before but can't do it now
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    (Original post by SunGod87)
    Given that p=secθ-tanθ and q=secθ+tanθ show that p=1/q

    Pretty sure I did this before but can't do it now
    pq = (secx - tanx)(secx + tanx)

    = sec²x - tanxsecx + tanxsecx - tan²x

    = sec²x - tan²x

    = 1

    pq = 1

    p = 1/q

    I used x instead of theta. Meh :p:
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    (Original post by seankhn)
    I doubt they'll go out of their way to cover something which is completely irrelevant to C3 like sequences and series. I have a suspicion it'll be something like using the laws of logarithms and then having to draw a graph.
    Me too :rolleyes:
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    seankhn: Thanks, it was the one I had done before, forgot how to do it lol
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    (Original post by SunGod87)
    seankhn: Thanks, it was the one I had done before, forgot how to do it lol
    I've got solutions for all those mixed exercise questions :cool:
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    What are even/odd functions? =o
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    Even functions:
    f(x) = f(-x)
    The function is a reflection of itself in the y-axis. Example: cosx

    Odd functions:
    f(x) = -f(x)
    The function is a 180 degree rotation of itself. Example: sinx
    • Thread Starter
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    Thanks man! For the 180 degree rotation, what does it mean by example:sinx?
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    Imagine drawing the postive side of sinx, and then rotating it 180° (about the origin). You'd get the negative part of it. So, f(x) = sinx is an odd function.
    See attachment...
    Attached Images
     
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    Ah skeen. Cheers =o)
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    (Original post by seankhn)
    No problem.


    Anyone had a go at that sin3x = cosx question yet? The interval is 0 to 360°

    sin3x = cosx
    sin(x+2x) = cosx
    sinxcos2x+cosxsin2x = cosx
    sin(1-2sin²x)+2cos²sinx = cosx
    sinx(1-2sin²x+2cos²x) = cosx
    sinx(1-2(sin²x+cos²x)) = cosx
    -sinx = cos x
    tanx = -1
    x = 135, 315
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    (Original post by Seth)
    sin3x = cosx
    sin(x+2x) = cosx
    sinxcos2x+cosxsin2x = cosx
    sin(1-2sin²x)+2cos²sinx = cosx
    sinx(1-2sin²x+2cos²x) = cosx
    sinx(1-2(sin²x+cos²x)) = cosx
    -sinx = cos x
    tanx = -1
    x = 135, 315
    After this stage.....

    sinx(1-2sin²x+2cos²x) = cosx



    Would factorising further not give you....

    sinx(1-2(sin²x-cos²x)) = cosx???

    If so, how do I then go about completing the question?

    Cheers.
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    there should not be a minus in your factorisation

    sin²x + cos²x = 1
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    (Original post by mik1w)
    there should not be a minus in your factorisation

    sin²x + cos²x = 1
    But it's -2sin²x + 2cos²x

    sin²x + cos²x isn't a factor of that.
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    why does sec^2x-tan^2x =1?

    EDIT: its cos tan^2x +1 = sec^2x
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    By the way, edexcel practice papers made by edexcel themselves are the best papers you can do. I've done the c2 ones and one of them is very much like the jan 05 paper. I'd recommend them over solomon papers.
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    Indeed. Btw, is it just me or does paper A3's first q not show up?
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    It doesnt show up.
    I need help with this.

    f(x) = 1/(x+1)(x-1)

    What is the range? The answers just say the range of f(x) is y where y>0
 
 
 
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