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Math Help - newbie differentation

  1. #1
    Newbie
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    newbie differentation

    hi im a newbie to mathes and have been doing calculus recently ive. Been given two formulas and need to differentiate themthem and solve the equation, ive had a good attempt at them. i would just like to confirm if they are corret.

    newbie differentation-diff.jpg
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  2. #2
    A Plied Mathematician
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    Your first one is incorrect, I think. Take the derivative first, without plugging in numbers. What do you get?

    Your second one is confusing. I'm not sure what you mean on the LHS of the equals sign.
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  3. #3
    MHF Contributor
    Grandad's Avatar
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    Hello lukebushnell

    The first one is:
    \dfrac{ds}{dt}= -15e^{-1.5t}
    When t=0.7
    \dfrac{ds}{dt}= -15e^{-1.05}
    =-5.25, correct to 3 s.f.

    The second one is correct to 2 s.f. ( 2.21 to 3 s.f.)

    Grandad
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  4. #4
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    hi , thanks for the quick reply,. sorry about the equation the bit befoere the = sgn should be i , because the answer is electrical current, and as for the first one im not sure on the answer, i cant rmeber from the exam. i thnik ill just have to wait to august to find out, but thanks for the reply , i appreciate it
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  5. #5
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    thanks grandad for the reply, that number does ring a bell but i have had so many numbers floating around my head so it could be any thing.
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