Saturday, September 26, 2015

Verify the relation f'(x)/f(x)=1+lnx, if f(x)=e^(ln((x)^x))?

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.

No comments:

Post a Comment

Can (sec x - cosec x) / (tan x - cot x) be simplified further?

Given the expression ( sec x - csec x ) / (tan x - cot x) We need to simplify. We will use trigonometric identities ...