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4.1 The Inverse Function f -1

(This is not to be confused with the reciprocal function, 1 / f.)

If g[f(x)] = x for x in some region R, then g is called the inverse of f and is defined on f(R).

We usually denote such g(x) as f -1(x).

The graph of g is obtained by reflecting the graph of f with respect to the line y = x.

Notice that the derivative of f -1 is the reciprocal of that of f, at corresponding points.

Proof

Example

Comment on uniqueness