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# Not Another Differentiation Question!! watch

1. Urrrrrrgh....a C3 differentiation question
It's a quick one though!
ln(1/3 x)...is the answer 3/x, as in the fraction 3 over x?
Thank you!!
2. Actually, is it 1/x?
3. The answer is simply 1/x. For ln(u), your derivative will be a fraction du/u (where du is the derivative of u). That means u=(1/3)x and du=1/3, giving you (1/3)/[(1/3)x] for your derivative, which simplifies to simply 1/x.

It's a good idea to note for all ln(ax), where x is a constant, the derivative will be 1/x as the a in the numerator and the a in the denominator will cancel each other out.
4. That makes seeeense....
THank you!

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Updated: January 15, 2010
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