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polymerase · #1 December 6th, 2007, 08:53 PM

If $f(x)=ln(ln\:x)$ , find the value of $f'(\frac{1}{e})$

Choices:

a) $-\frac{1}{e}$
b)undefined
c) $\frac{1}{e}$
d) $2e$
e) $\sqrt{e}$

alright, heres where im at right now:

1)It could be undefined because $\frac{1}{e}$ is not in the domain of f(x)?
2)the answer is $-e$ and my prof made a mistake(seems unlikely since he's been doing this for 20 years)?
3)my friend says its $\frac{1}{e}$ ?

Can anyone confirm which is correct with justification?

Thanks!