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Thread: [SOLVED] natural log

  1. #1
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    [SOLVED] natural log

    $\displaystyle P=130e^{-.000155h}$
    find h when P = 8.5

    $\displaystyle 8.5=130e^{-.000155h}$

    answer is 17600

    I take LN of both sides then solve for h but I get -2353?
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  2. #2
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    Quote Originally Posted by brentwoodbc View Post
    $\displaystyle P=130e^{-.000155h}$
    find h when P = 8.5

    $\displaystyle 8.5=130e^{-.000155h}$

    answer is 17600

    I take LN of both sides then solve for h but I get -2353?
    What steps did you do? Mine are below to check against



    $\displaystyle e^{-0.000155h} = 8.5/130$

    take natural logs:

    $\displaystyle -0.000155h = ln{(\frac{8.5}{130})}$

    $\displaystyle h = \frac{1}{-0.000155}\cdot ln{(\frac{8.5}{130})} = 17600 (3sf)$
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  3. #3
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    Lightbulb

    k I got It, I was typing it into my calculator wrong, thanks again
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