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Need help with this logs question.?

Log(base 2)x + Log(base 3)x = 1

I know it is a change of base problem (rule 8) but because the bases are primes I'm stuck. Any help would be greatly appreciated

1 Answer

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  • ?
    Lv 7
    7 years ago
    Favourite answer

    There is a property where logs can be converted to natural logs regardless of whatever base

    If you have log (base y) x where x and y are reals, then

    log (base y) x = (ln x) / ln(y)

    so you can rewrite this as

    [ ln(x) / (ln 2) ] + [ ln(x) / ln(3) ] = 1

    ln(x) (( 1 / ln(2) + 1 /(ln 3)) = 1

    1 / ln(x) = [ 1 / ln(2) + 1 /(ln 3) ]

    taking reciprocal of both sides,

    ln(x) = [ 1 / ln(2) + 1 /(ln 3) ]

    x = exp ( [ 1 / ln(2) + 1 /(ln 3) ] ^(-1) )

    x = 1.53

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