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Some change of variable?

  1. May 20, 2012 #1
    let x=r^2.
    if we have already d/dr, how to find d/dx?

    I was saying, d/dr=(d/dx)*(dx/dr)=(d/dx)*2r ?

    But am doubting it?
     
  2. jcsd
  3. May 20, 2012 #2

    tiny-tim

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    Hi M. next! :smile:

    (try using the X2 button just above the Reply box :wink:)
    Yes, that's a correct use of the chain rule, it's fine. :smile:

    (though i'd write it 2r*dr/dx, to leave the d/dx free to have-a-go at the next thing! :wink:)
     
  4. May 20, 2012 #3
    Thanks Tim :) but my doubting results from.. Well, I recall from class that there was a radical 2 and not only 2?
     
  5. May 20, 2012 #4

    tiny-tim

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    √2 ?

    i can't think where that would come from :confused:
     
  6. May 20, 2012 #5
    Neither could I, thanks tim,
    have a good day
     
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