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Solve logarithm equation?

log x^2 = (log x)^2

Instructions say to use any method, but I'm not sure what would be the best and easiest to learn/memorize.

3 Answers

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  • 7 years ago
    Favorite Answer

    log x^2 = (log x)^2

    2log x = log x logx

    2 = log x logx / logx

    Cancel down.

    2 = log x

    Antilog.

    x = 10^2

    x = 100

  • 7 years ago

      Note:  ( log(x) )²  is normally written as:  log ² (x)

        log( x² ) = log ² (x)   ...  assuming base ten logs.

       2 log(x) = log ² (x)

               0 = log ² (x)  –  2 log(x)

               0 = log(x) • [ log(x)  –  2 ]

          log(x) = 0       and       log(x)  –  2 = 0

                x = 1           ...             log(x) = 2

                              ...                       x = 10² = 100

    So there are two solutions that are valid in the initial log equation

    as shown below:

        log( x² ) = log ² (x)

        log( 1² ) = log ² (1)   ...  x = 1   solution

         log( 1 ) = log ² (1)

                0 = (0)²   ...  TRUE

              log( x² ) = log ² (x)

            log( 100² ) = log ² (100)   ...  x = 100   solution

        log( 10000 ) = log ² (100)

                      4 = (2)²   ...  TRUE

  • ?
    Lv 7
    7 years ago

    First, log x^2 = 2log x so now we have 2log x = (log x)^2 so to simplify the writing I'll write L for log x so we now have 2L = l^2 so L^2 - 2L = 0 giving l(L - 2) = 0 so L = 0 or L = 2 i.e. log x = 0 or log x = 2 and that gives us x= 1 or x = 100.

    Source(s): Retired Maths Teacher
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