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Math Help - 4th derivative

  1. #1
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    4th derivative

    If f(x) = (2+3x)^4, then find the 4th derivative of f(x).

    A. 0
    B. 4!(3)
    C. 4!(3^4)
    D. 4!(3^5)
    E. 4!(2+3x)
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by DINOCALC09 View Post
    If f(x) = (2+3x)^4, then find the 4th derivative of f(x).

    A. 0
    B. 4!(3)
    C. 4!(3^4)
    D. 4!(3^5)
    E. 4!(2+3x)
    C.

    think about it, why is that? (you don't have to actually find the fourth derivative explicitly, you can think through it)
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  3. #3
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    there are 4 powers so that wil cross out making it 0 which is letter A? correct?
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by DINOCALC09 View Post
    there are 4 powers so that wil cross out making it 0 which is letter A? correct?
    no, i told you the answer is C.
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  5. #5
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    f(x) = (2+3x)^4

    is it something to do with losing the x making it 3^4??

    i dont know
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  6. #6
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    Quote Originally Posted by DINOCALC09 View Post
    If f(x) = (2+3x)^4, then find the 4th derivative of f(x).

    A. 0
    B. 4!(3)
    C. 4!(3^4)
    D. 4!(3^5)
    E. 4!(2+3x)
    f'(x)=4\cdot3(2+3x)^3.

    So we'll have 4! on the final expression and by the chain rule, 3^4, can you see that?
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