Question 915027
You have three choices.  Your composition equation given is to compose a function with itself.  Just test every choice I, II, and III, and see which one gives x as a result (when simplified).


What if you had a forth choice...
IV.  {{{f(x)=-1/x}}}
Would this composed of itself be x?


{{{f(f(x))=-1/(-1/x)}}}
{{{1/(1/x)=x}}}
I did not expect that, but this function is also its own inverse; meaning this function composed with itself will give back the input variable.