let f(x)=x/x-4. find a function y=g(x) so that (fog)(x)=x (f round g) any help?

Question

let f(x)=x/x-4. find a function y=g(x) so that (fog)(x)=x    (f round g) any help?

goformit100 · Answer

just diffrentiate it

anonymous · Answer

how? i am new at this round thing... can u give me an ex?

ajprincess · Answer

Let $f(x)=x+1$ and $g(x)=x^2$. 
$fog(x)=f(g(x))$.
To find $fog(x)$
put g(x) in place of x in f(x).
That is
$f(g(x))=(g(x))+1$
          $=x^2+1$
Getting it @aboulmich2?

anonymous · Answer

|dw:1349942482654:dw|

goformit100 · Answer

yes

anonymous · Answer

yes this i got it but in reverse if i have only f(x) how can i find g(x)?

anonymous · Answer

i mean how to solve the question i wrote in details plzz

ajprincess · Answer

f(x)=x/x-4 and ur g(x)=y.
To find f(g(x))
u wil put g(x) in place of x in f(x) right?

anonymous · Answer

right

ajprincess · Answer

f(g(x))=y/y-4
Also u r given that f(g(x))=x.
So
x=y/y-4
Nw solve for y to find g(x)

anonymous · Answer

okayy i got it now thanks everyone

ajprincess · Answer

yw:)