Calculation question

  • Thread starter asdf1
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  • #1
asdf1
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for this equation, y=vx, it's the same as v=y/x
however, if i differenate the 1st equation, dy/dx=v+x*dv/dx
and if i differenate the 2nd equation, dv/dx=(1/x)*dy/dx + [-1/(x^2)]y
but both differenated equations don't seem the same...
does somebody know where my calculuations went wrong?
 

Answers and Replies

  • #2
Astronuc
Staff Emeritus
Science Advisor
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dv/dx=(1/x)*dy/dx + [-1/(x^2)]y

becomes x (dv/dx) = dy/dx - y/x, but v = y/x

so x (dv/dx) = dy/dx - v

or

x (dv/dx) + v = dy/dx, which is same as other equation.
 
  • #3
asdf1
734
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thank you very much!!! :)
 

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