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Math Help - derivative of log function

  1. #1
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    derivative of log function

    just want to make sure i'm doing this problem right, any help is appreciated.

    find derivative:

    log7x^2-1

    = log7 + logx^2-1

    = lnx^2-1 / ln7

    =ln(x+1)(x-1) / ln7

    = 1/ln7 + (1/x+1 * 1/x-1)

    ??
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  2. #2
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    Quote Originally Posted by JGaraffa View Post
    just want to make sure i'm doing this problem right, any help is appreciated.

    find derivative:

    log7x^2-1

    = log7 + logx^2-1

    = lnx^2-1 / ln7

    =ln(x+1)(x-1) / ln7

    = 1/ln7 + (1/x+1 * 1/x-1)

    ??
    Please use brackets where they're needed, this is too hard to read.

    Is the function

    y = \ln{(7x^2)} - 1?
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  3. #3
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    Here is the way to find the derivative of log functions;

    \frac{Derivative~of ~inside~of~ log}{inside~ of~ log}

    Is you function \log(7x^2-1)?

    If yes, from the above rule \frac{Derivative~of ~7x^2-1}{7x^2-1}=\frac{14x}{7x^2-1}
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  4. #4
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    ah i knew i forgot brackets somewhere.

    the original problem was

    log7(x^2-1)
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