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Math Help - Math HELP! bugging me

  1. #1
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    Math HELP! bugging me



    What am I doing wrong here? I have applied the chain rule, but the answer is actually 92/9.
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  2. #2
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    Re: Math HELP! bugging me

    How do you set up the chain rule?

    And where is 92/9 coming from? I keep getting -184/9.
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  3. #3
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    Re: Math HELP! bugging me

     \frac{dy}{dx}= \frac{dy}{du}\frac{du}{dx} = 10u\frac{du}{dx}+3\frac{du}{dx}=10\frac{18}{x^2+5} \frac{-36x}{(x^2+5)^2}+ 3\frac{-36x}{(x^2+5)^2}= \frac{-6480x}{(x^2+5)^3} -\frac{108x}{(x^2+5)^2}

    phys251 is right.

    Plugging in x=2 gives -184/9.
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  4. #4
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    Re: Math HELP! bugging me

    Thanks guys, it appears I forgot to multiply 3 by the "u" prime..

    Anyways, I think the back of the textbook is wrong because im getting -184/9 aswell.
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