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    Looking at the 2015 paper for C4 edexcel on question 6 ii)
    So I get I have to find the solution to the equation

    Name:  1.gif
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    But how does this integrate into this? The mark scheme just says its so.

    2(sin^3 x)/3 ?
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    (Original post by Dieselblue)
    Looking at the 2015 paper for C4 edexcel on question 6 ii)
    So I get I have to find the solution to the equation

    Name:  1.gif
Views: 41
Size:  997 Bytes

    But how does this integrate into this? The mark scheme just says its so.

    2(sin^3 x)/3 ?
    Done by recognition.

    Follows from:

    \displaystyle\frac{d}{dx}(f(x))^  n =nf'(x)(f(x))^{n-1}

    Identify f(x) and reverse the process.
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    (Original post by Dieselblue)
    Looking at the 2015 paper for C4 edexcel on question 6 ii)
    So I get I have to find the solution to the equation

    Name:  1.gif
Views: 41
Size:  997 Bytes

    But how does this integrate into this? The mark scheme just says its so.

    2(sin^3 x)/3 ?
    If you have trouble using the recognition method in the above post (like me), you can also use substitution if it makes more sense for you.



    Let






    Substituting dy back into original integral















    Obviously this method takes a lot more time than recognition, so you should probably try to learn that, but use this as a backup. Substitution can help to make complicated integrals easier, so if things aren't working out give substitution a try.
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    Alternatively you could of used the addition formulae

    cos(A+B) - cos(A-B) = -2SinASinB
 
 
 
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