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    someone help me with c2 differentiation, I dont understand it with shapes
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    Hello I've moved this to maths for you.

    Could you post an example of a question you are struggling with?
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    (Original post by rayquaza17)
    Hello I've moved this to maths for you.

    Could you post an example of a question you are struggling with?

    for example if you have a look at the edexcel june 2014 c2 paper all of question 10.

    I really do not understand any of it

    please help!
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    (Original post by Mr revision)
    for example if you have a look at the edexcel june 2014 c2 paper all of question 10.

    I really do not understand any of it

    please help!
    So others don't have to find the question, here's the paper:
    http://qualifications.pearson.com/co...-June-2014.pdf

    Please post a link to the question in future threads.

    So starting with a), how do you work out the volume of a prism? Please post your thoughts and any working that you have done.
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    (Original post by Mr revision)
    for example if you have a look at the edexcel june 2014 c2 paper all of question 10.

    I really do not understand any of it

    please help!
    You use the relationship between an area and a volume
    (which it gives as 9600cm^3)

    take the area of the trapezium ((h(a+b))/2) which for this question:
    a(x) = ((4x(9x+6x))/2) = 30x^2

    the volume is the area * length (y) so,
    y * a(x) = 9600cm^3

    therefore

    y = 9600cm^3/a(x) = 9600cm^3/30x^2 = 320/x^2
    --------------------------------------------------------------------
    surface area:
    you take:
    S = 2a(x) + y(6x) + y(9x) + y(4x) + y(5x)
    = 60x^2 +y(24x)
    = 60x^2 + (320/x^2) * (24x)
    = 60x^2 + (7680/x)
    ---------------------------------------------------------------------
    finding minimum of S (when dS/dx = 0)
    ---------------------------------------------------------------------
    you can justify it's a minimum if S'' is positive (>0) for the value of S you found in 10 (c)
 
 
 
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