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math

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Solve log.
2 log (x-1)= log (x+1)

the answer is 3 but i don't know how to get it...Any one hint or suggestion will be greatly appreciated :)

  • math -

    From previous ans:

    2 log (x-1)= log (x+1)
    log[(x-1)²] = log(x+1)
    Take antilog:
    (x-1)²=x+1
    Expand and solve quadratic:
    x²-3x=0
    x(x-3)=0

    x=0 is not admissible as solution because log(-1) is undefined.
    The remaining answer is therefore x=3.

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