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Derivative of quotient with same variables on top and bottom

  • #1

Homework Statement



a=g.[(M-m)/(M+m)]

how do i go about finding the partial derivative wrt m?

Homework Equations





The Attempt at a Solution



i started by rearranging it to the form a=g.(M-m)(M+m)^-1, i used the chain rule to find the derivative of (M+m)^-1 to be -(M+m)^-2 but i'm not sure where to go from there or even if that was the right approach to take. any help?

thanks
 

Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
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I don't see why you would have a problem with this. Would you be able to find the derivative, with respect to x, of (x- m)/(x+ m) if m were a constant? What about (M-x)/(M+ x) if M is a constant? It's exactly the same thing.

You can write (M-m)(M+m)-1 and use the chain rule together with the product rule or you can keep it as (M-m)/(M+m) and use the quotient rule.
 

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