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Deriving the Quotient Rule


Date: 9/5/95 at 17:11:23
From: Anonymous
Subject: math question

Question:
Hi!
I'm a Swedish student at Chalmers and my math problem is:
how do I prove this derivation?

             (f/g)' = gf'-fg'/ g^2


Date: 9/6/95 at 12:23:14
From: Doctor Ken
Subject: Re: math question

Hello!

You know, I don't think this is a dumb question at all!  This stuff can be
really tough and scary the first time you see it.

I think the easiest way to do this derivation is to write f/g as f*g^(-1).
Then you can use the product rule and the power rule to get the answer.  In 
fact, since the quotient rule (what you're trying to derive) is kind of hard
to remember, I usually end up re-deriving this every time I want to use it
or teach it to someone.

Good luck!

- Doctor Ken,  The Geometry Forum

    
Associated Topics:
High School Calculus

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