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    Hi, I need urgent help! Can anyone tell me how re-arrange this:

    y = 18.655Ln(x) + 46.681

    so i can get x when y=50

    Any help is really great, thanks
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    (Original post by Arthurk)
    Hi, I need urgent help! Can anyone tell me how re-arrange this:

    y = 18.655Ln(x) + 46.681

    so i can get x when y=50

    Any help is really great, thanks
    Is it just me or is this really easy....i'll wait cos if i'm wrong i'll look silly.
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    (Original post by Arthurk)
    Hi, I need urgent help! Can anyone tell me how re-arrange this:

    y = 18.655Ln(x) + 46.681

    so i can get x when y=50

    Any help is really great, thanks
    50 = 18.655ln x + 46.681

    => 50 - 46.681 = 18.655ln x

    => (50 - 46.681)/18.655 = ln x

    => ln x = 0.1779...

    => x = e^0.1779...

    => x = 1.194...
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    (Original post by Nylex)
    50 = 18.655ln x + 46.681

    => 50 - 46.681 = 18.655ln x

    => (50 - 46.681)/18.655 = ln x

    => ln x = 0.1779...

    => x = e^0.1779...

    => x = 1.194...
    wow, i feel really stupid... but then, maths was never my strong suit...
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    Yeah, i feel pretty stupid too now. Is it really that simple? i always thought if you multiplied a natural log it led to some weird shenanigans that meant you couldn't just divide each side by that number. Oh, well, i guess i just like to make things difficult!

    Cheers
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    (Original post by Arthurk)
    Yeah, i feel pretty stupid too now. Is it really that simple? i always thought if you multiplied a natural log it led to some weird shenanigans that meant you couldn't just divide each side by that number. Oh, well, i guess i just like to make things difficult!

    Cheers
    One of the log rules is: nlog a = log (a^n)

    You could also solve for x using that:

    50 - 46.681 = 18.655ln x

    => ln (x^18.655) = 50 - 46.681

    => x^18.655 = e^(50 - 46.681)

    Then just raise both sides to power 1/18.655.
 
 
 
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