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Math Help - help finding derivative

  1. #1
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    help finding derivative

    Hello!

    I'm having trouble when i try to derivate this function:

    y=sin^6x+cos^6x+3sin^2xcos^2x

    Any idea?

    Thanks.

    P.s solution in my book is 0.
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  2. #2
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    Quote Originally Posted by GreenMile View Post
    Hello!

    I'm having trouble when i try to derivate this function:

    y=sin^6x+cos^6x+3sin^2xcos^2x

    Any idea?

    Thanks.

    P.s solution in my book is 0.
    Hello !
    This answer is effectively 0
    You can derivate (awful job !)
    Or you can see that
    (sin^2x+cos^2x)^3=sin^6x+3sin^4xcos^2x+3sin^2xcos^  4x+cos^6x
    but
    sin^2x+cos^2x=1
    therefore
    1=sin^6x+3sin^2xcos^2x(sin^2x+cos^2x)+cos^6x

    1=y and then y'=0
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  3. #3
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    Sorry how did u get (sin^2x+cos^2x)^3=sin^6x+3sin^4xcos^2x+3sin^2xcos^  4x+cos^6x
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  4. #4
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    (a+b)^3 = a^3 + 3a^2b + 3ab^2 + b^3
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