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Math Help - Another Second Derivative question

  1. #1
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    Another Second Derivative question

    Find f''(x) if f(x)=4e^{7x^4}

    Heres my work but I think its wrong b/c I cant finish it

    f'(x)=4e^{7x^4}(28x^3)

    =112x^3e^{7x^4}

    f''(x)=112x^3e^{7x^4}(28x^3)+e^{7x^4}(336x^2)
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by McDiesel View Post
    Find f''(x) if f(x)=4e^{7x^4}

    Heres my work but I think its wrong b/c I cant finish it

    f'(x)=4e^{7x^4}(28x^3)

    =112x^3e^{7x^4}

    f''(x)=112x^3e^{7x^4}(28x^3)+e^{7x^4}(336x^2)
    you are right so far. now just simplify
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  3. #3
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    f''(x)=112x^3e^{7x^4}(28x^3)+e^{7x^4}(336x^2)

    f''(x)=3136x^6e^{7x^4}+336x^2e^{7x^4}

    Yes/no?
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  4. #4
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    Yes, that's correct . You can factorise if you wish!

     f"(x) = 16x^{2}e^{7x^{4}}\ (196x^{4} + 21)

    I hope that helps.

    ILoveMaths07.
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