The Self-Inverse Function

This sounds really weird or complex but it's not.

Basically a self-inverse function is just a function that gives you the same answer when you do the function to the answer.

Wot?


Alright. Say you have a function f(x) = 4-x

Say x = 2

4-2 = 2.

Now apply the answer to the function

4-2 = 2.

Same answer.


Try again f(x) - 7-x

Say x - 5.

7-5=2.

7-2=5

We have x again.


And f(x) - 10-x

x=4

10-4 = 6

Put 6 into it:

10-6=4.

Brings us back to our starting point with x.


When you do the operation twice, finding the function of the answer, you get your starting value of x.
Reciprocals always give self-inverses too.