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Confuing derivative

  1. Jul 23, 2012 #1
    can someone please explain this?

    [tex]\frac{d}{dt} \frac{P}{T}=\frac{1}{T} ( \frac{dP}{dt}- \frac{dlnT}{dt})[/tex]
     
  2. jcsd
  3. Jul 23, 2012 #2

    tiny-tim

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  4. Jul 23, 2012 #3
    im not sure...

    but i just tried quotient rule and it worked out?...
    [tex] \frac{d}{dt} \frac{P}{T}= \frac{T \frac{dP}{dt}-P \frac{dT}{dt}}{T^2}=\frac{1}{T} \frac{dP}{dt} - \frac{P}{T^2} \frac{dT}{dt}[/tex] ...etc.
    how exactly do you implement chain rule after you use product rule? i would like to know. thanks in advance!
     
    Last edited: Jul 23, 2012
  5. Jul 23, 2012 #4

    tiny-tim

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    ooooh, it's T-time! :tongue2:

    chain rule …

    d(lnT)/dt = d(lnT)/T dT/dt :wink:
     
  6. Jul 23, 2012 #5
    thanks!...i need to get used to using the chain rule...we never really used it much in my calculus classes from back in the day...
     
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