f: [−1, 1] → R is given as![]()
Let f(x) = f(y).

∴ f is a one-one function.
It is clear that f: [−1, 1] → Range f is onto.
∴ f: [−1, 1] → Range f is one-one and onto and therefore, the inverse of the function:
f: [−1, 1] → Range f exists.
Let g: Range f → [−1, 1] be the inverse of f.
Let y be an arbitrary element of range f.
Since f: [−1, 1] → Range f is onto, we have:

Now, let us define g: Range f → [−1, 1] as

∴gof =
and fog = ![]()
f−1 = g
⇒ ![]()