To verify the given identity, we'll have to differentiate
the function f(x):
f'(x)
=e^[ln((x)^x)]*[ln((x)^x)]'
[ln((x)^x)]' =
[x*ln(x)]'
We'll use the product
rule:
(u*v)' = u'*v +
u*v'
[x*ln(x)]' = x'*ln x +
x*[ln(x)]'
[x*ln(x)]' = ln x +
x/x
[x*ln(x)]' = ln x + 1
So,
the derivative of the function f(x) is:
f'(x) =
e^[ln((x)^x)]*(ln x + 1)
But e^[ln((x)^x)] =
f(x).
f'(x) = f(x)*(ln x +
1)
We'll divide both sides by f(x) and we'll
get:
f'(x)/ f(x) = (ln x + 1)
q.e.d.
We notice that the identity
f'(x)/f(x)=1+lnx is verified.
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