Invertible Functions

Functions of Class 11

Invertible Functions

Let f : A→B be a one one and onto function then there exists a unique function g : B→A.

Such that f(x) = y ⇒ g(y) = x = f -1(y), ∀ x ∈ A and y ∈ B.

Then g is said to be the inverse of f.

And fo f -1 = f -1o f = I (an identify function)

and fo f -1 (x) = f -1o f (x) = I(x) = x

⇒ f {f -1 (x)}= x.

Note: If f is one to one then f has an inverse and conversely if f has an inverse then f is one to one from A to B and g is one to one from B to C then fo g is one to one from A to C and (fo g)-1 = g-1o f -1.

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