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    I have no idea how to solve the whole of Q7) .

    Please help me
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    well first start by differentiation in part a and lets see where you get
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    (Original post by clad in armour)
    well first start by differentiation in part a and lets see where you get
    So dy/dx = 2cosX - 1

    Eeek... is that correct?
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    (Original post by clad in armour)
    well first start by differentiation in part a and lets see where you get
    ...this

    and @OP as you shud prolly know dy/dx gives you the gradient at any point of a curve.Specific Maximum and minimum values are therefore found (in some functions - def in cos and sin fs) when gradient is 0. But remember you'll never kno whther its a max or min til u diff again
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    (Original post by APonderingMind)
    So dy/dx = 2cosX - 1

    Eeek... is that correct?
    yes, and the question asks for the maximum, so you may know as mentioned that dy/dx = o.....
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    (Original post by clad in armour)
    yes, and the question asks for the maximum, so you may know as mentioned that dy/dx = o.....
    Uh huh, and I did this:

    2cosX - 1 = 0
    cos X = 1/2
    X= 1/3Pi

    The answer at the back of my text book says it's root3 - 1/3Pi

    So where do I go from here?
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    But y=2sinx -x

    Not y = sin2x...
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    (Original post by R3L4Y)
    remember it was sin2x ...
    It wasn't. It was y=2sinx - 1.
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    (Original post by APonderingMind)
    But y=2sinx -x

    Not y = sin2x...
    hahaha I just realized this thnx
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    (Original post by davidmarsh01)
    It wasn't. It was y=2sinx - 1.
    it was a test? lol
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    (Original post by APonderingMind)
    Uh huh, and I did this:

    2cosX - 1 = 0
    cos X = 1/2
    X= 1/3Pi

    The answer at the back of my text book says it's root3 - 1/3Pi

    So where do I go from here?
    your not finished yet, now you know there is a stationary point at x= 1/3pi, the question asks about the maximum, differentiate again
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    (Original post by clad in armour)
    your not finished yet, now you know there is a stationary point at x= 1/3pi, the question asks about the maximum, differentiate again
    Second derivative: -2sinX

    OOh...yay! I found the answer now.

    Subbed 1/3Pi into second derivative to find that it = -root3. This means it is the maximum value.

    So then I subbed it into the curve and got the answer root3 - 1/3Pi. =D

    Thanks for forcing me to do my own maths question, it actually helped!
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    (Original post by APonderingMind)
    Second derivative: -2sinX

    OOh...yay! I found the answer now.

    Subbed 1/3Pi into second derivative to find that it = -root3. This means it is the maximum value.

    So then I subbed it into the curve and got the answer root3 - 1/3Pi. =D

    Thanks for forcing me to do my own maths question, it actually helped!
    glad to help, you know how to do the other parts?
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    (Original post by clad in armour)
    glad to help, you know how to do the other parts?
    Yes I can do the other parts thanks =)
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    (Original post by APonderingMind)
    Yes I can do the other parts thanks =)
    cool
 
 
 
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