The answers to exercise marked [BB] can he found in the Back of the Book.Let A be a subset...

The answers to exercise marked [BB] can he found in the Back of the Book.

Let A be a subset of R and suppose ƒ: A → A is a function with the property that f−1(x) = for all x ∈ A.

(a) Show that 0 ∉ A.

(b) Show that f4 = ιA, the identity function on A. (By f4, we mean ƒ o ƒ o ƒ o ƒ.)