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    (Original post by EspDe97)
    Does anyone know how to do this question?

    sin(A+B) - sin(A-B) / cos(A-B) - cos(A+B) = cotA
    Using the result of part (b) and the exact values of sin 60° and cos 60°,
    (c) find an exact value for cot 75°in its simplest form.
    Can you show us the rest of the question?
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    Can anyone help me to understand how to find 2c?
    As it's the inverse of f(x), the domain will be the range of f(x).. (right?) That's all I know

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    (Original post by Sakchuu)
    Hey, when finding/proving a root, do you sub the values into a) y=f(x) or b) f'(x)?
    f(x)!!!
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    (Original post by studentwiz)
    how would you use part a) to do b
    this is how i would do it, havent checked the MS tho
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    (Original post by studentwiz)
    how would you use part a) to do b
    Please what paper is this from?
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    (Original post by studentwiz)
    question 1 part b https://b3755649dbd1afe3db91a899c3b9...%20Edexcel.pdf

    when Expand I get 9x^2-30x+24 but I dont get one solution being x=2 ?
    Not sure where you went wrong, probably a simple factorizing error


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    (Original post by moeeahmed)
    Can someone help me with this question please?

    The function g is defined byg : x= ln(2x), x >0

    (c) Solve the equation g(x) + g(x2) + g(x3) = 6 giving your answer in its simplest form.

    The answer is (e/root2) June 2014(R) paper
    Put x in for g(x) then x^2 in for g(x^2) then x^3 in for g(x^3). You'll get ln(2x) + ln(2x^2) + ln(2x^3) = 6
    Use log laws to solve
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    (Original post by ridirahman)
    Ohh okay I think I understand I will need to practice these type of questions more thanks for helping!
    No problem man, good luck tomorrow!
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    (Original post by EspDe97)
    Does anyone know how to do this question?

    sin(A+B) - sin(A-B) / cos(A-B) - cos(A+B) = cotA
    Using the result of part (b) and the exact values of sin 60° and cos 60°,
    (c) find an exact value for cot 75°in its simplest form.
    Since A=75

    sin(75+15) -(sin75-15)/cos(75-15)-cos(75+15) =cot75 (value of B can be anything)
    => sin(90)-sin(60)/cos(60)-cos(90)=cot(75)
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    (Original post by anndz3007)
    Since A=75

    sin(75+15) -(sin75-15)/cos(75-15)-cos(75+15) =cot75 (value of B can be anything)
    => sin(90)-sin(60)/cos(60)-cos(90)=cot(75)
    Thank you so much!
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    can anyone link me the June 2013 R paper? thanks!
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    So with maximums and stuff.
    When R is maximum, cos(x+a)=-1 and R is minimum, cos(x+a)=1?

    Am i right?
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    any tips or tricks to remember tomorrow?
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    (Original post by frozo123)
    can anyone link me the June 2013 R paper? thanks!
    All the papers you will ever need:
    http://www.physicsandmathstutor.com/...rs/c3-edexcel/
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    what are the proofs for tomorrow do we need to remember?
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    Could someone please explain why g^-1gf(x)=f(x) ?


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    (Original post by Nirm)
    So with maximums and stuff.
    When R is maximum, cos(x+a)=-1 and R is minimum, cos(x+a)=1?

    Am i right?
    Yes. However, there may be situations where the maximum value of a function including Rcos(x+a) is when cos(x+a) = -1 or even when it equals 0 - it depends on the context of the function
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    (Original post by TeddyKC)
    Could someone please explain why g^-1gf(x)=f(x) ?


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    g^-1(x) and g(x) are inverse functions and so they cancel each other out, in the same way that lne = 1
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    (Original post by Nirm)
    So with maximums and stuff.
    When R is maximum, cos(x+a)=-1 and R is minimum, cos(x+a)=1?

    Am i right?
    nahh depend on the situationn
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    (Original post by frozo123)
    can anyone link me the June 2013 R paper? thanks!
    http://www.physicsandmathstutor.com/...rs/c3-edexcel/
 
 
 
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