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Thread: equations

  1. #1
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    equations

    Find the solution of the logarithmic equation



    &; Find the solution of the logarithmic equation



    ?????? no clue!
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by evinez View Post
    Find the solution of the logarithmic equation

    $\displaystyle log_2(x^2 - 5x - 20) = 2$

    $\displaystyle x^2 - 5x - 20 = 2^2 = 4$

    etc.

    -Dan
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    Forum Admin topsquark's Avatar
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    Quote Originally Posted by evinez View Post

    $\displaystyle log(x) + log(x - 20) = log(7x)$

    $\displaystyle log(x(x - 20)) = log(7x)$

    $\displaystyle x(x - 20) = 7x$

    etc.

    -Dan
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  4. #4
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    Hello,

    For the second one, remember that $\displaystyle \log(a)+\log(b)=\log(a+b)$

    Then if $\displaystyle \log(x)=\log(y)$, $\displaystyle x=y$

    remember that x has to be positive and superior to 20 as x and x-20 have to be positive
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