<human>:  Why is it true that f(x) = f for all x in the function ‘f(x) = f’?
<bot>: That’s a good question. It’s true because f is an inverse of f. In math, an inverse of a function is a function that is the inverse of the original function. In this case, f is the inverse of f, so it is true that f(x) = f for all x.