ok who can integrate f'/(f-f') with respect to x
and yes f is a function of x
i can't think right now

Question

anonymous · Answer

is that related to other problem (f g)'=(f'g') ?

myininaya · Answer

yes

myininaya · Answer

i don't think we can do it by any elementary ways

anonymous · Answer

did you try 
$$\int \frac{x^3}{x^3-3x^2}dx$$ or 
$$\int\frac{\sin(x)}{\sin(x)-\cos(x)}dx$$?maybe there is a pattern?

myininaya · Answer

maybe i should look for a pattern
i will be back

anonymous · Answer

well i tried them both with wolfram. then i went to http://www.wolframalpha.com/input/?i=intgerate+f%28x%29%2F%28f%28x%29-f%27%28x%29%29dx

anonymous · Answer

results not promising

myininaya · Answer

sorry the top should be f' too 
ok for real though i will be right back

anonymous · Answer

now you tell us
!

myininaya · Answer

lol no it was f' all the long 
satellite you are getting old

myininaya · Answer

i see a pattern with polynomials or monomials anyways

myininaya · Answer

no not a pattern

myininaya · Answer

just one for monomials

myininaya · Answer

i give up
i need to do my own work now

anonymous · Answer

A simple answer occurs to me, $$\int\limits_{}^{}f \prime/(f-f \prime) = \ln(f-f \prime ) $$ if and only if  $$f \prime \prime=0$$ so formula will only work for monomials like you just said

anonymous · Answer

wolfram says its a nonlinear differential equation, had the same feeling when I saw it, http://www.wolframalpha.com/input/?i=integrate+a%27%2F%28a-a%27%29