You can use the trigonometric identity

.

The requirement that

eliminates -1/6 from being another solution.
Answer:
4/5 is fully reduced
Step-by-step explanation:

Here we go ~
In the above question, it is given that :

A.) Find f(2) :


or

B.) Find
:

so, we can write it as :



Now, put x =
, and y = x and we will get our required inverse function ~

C.) Find
:



Yes it does and it would also be true if the y was 4 or 6 because 2 plays into all of those but it would be false if it was something like 5