Posted by **Marissa** on Friday, August 15, 2008 at 12:41am.

What is the derivative of:

a) cos(3x)

b) π/x

I did (a) just by following chain rule:

-sin(3x)*3

so it's -3sin(3x)

Is that correct?

I'm not completely sure how to do (b). Would it just be like the derivative of 1/x? That's -1/(x^2), would it be -π/(x^2) ?

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