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Math short but tricky

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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 :)

  • short and sweet -

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

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

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