posted by sh .
Find the derivative of
ln can't be negative. Is the derivative correct?
no, the second part of your product rule is not correct
lets just differentiate
1 - 4^x
that would be (-4^x)(ln4)
my final answer would be
f '(x) = (1-4^x) + x(-4^x)(ln4)
= 1 - 4^x - x(ln4)(4^x)
So the negative is not included,
for example f(x)=-2^x
f'(x) would be (-2^x)(ln2)?
I think you got it.
in your example you could look at -4^x