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precalculus

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solve the following equation show all work log4(x-4)= -1.

  • precalculus -

    by definition:

    log4 (x-4) = -1
    is equivalent to
    x-4 = 4^-1
    x-4 = 1/4
    x = 1/4 - 4
    = -15/4

    so we would have log (-3/4-4)
    but we cannot take the log of a negative, so ....
    no solution.

  • precalculus -

    log takes on all real values for its range. So, something's wrong here.

    x - 4 = 1/4
    x = 1/4 + 4
    x = 17/4

    log4(17/4 - 4) = log4(1/4) = -1

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