Math Is Fun Forum

Zeeshan 01

Member

Registered: 2016-07-22

Posts: 746

Inverse of function

What is inverse of a function please explain me with graph after this I post questions

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Malik

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Inverse of function

hi

It is a second function that maps each element in the codomain back to the element in the domain.

eg.  If f(x) = 2x then the inverse function is x/2

eg.  If g(x) = sin(x) then the inverse is asin(x) or sometimes written arcsin(x)

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Zeeshan 01

Member

Registered: 2016-07-22

Posts: 746

Re: Inverse of function

How??? Proov

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Malik

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Inverse of function

It is how an inverse function is defined.  Say the function does this:

Domain                             Range
   3  ------------------------>   7
   8  ------------------------>   2
   9  ------------------------>   0

Then the inverse function will be:

Domain                             Range
   7  ------------------------>   3
   2  ------------------------>   8
   0  ------------------------>   9

So you just have to look at which number maps onto which and reverse the direction of the mapping.

Please post a question and hopefully it will become clearer.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Zeeshan 01

Member

Registered: 2016-07-22

Posts: 746

Re: Inverse of function

That not a Proov that only word explaination of inverse

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Malik

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Inverse of function

Sorry but I do not know what you want to be proved.  What question?

Have a look at this page: http://www.mathsisfun.com/data/function-grapher-old.php

Enter a function (say 2x) and a second function, x/2.  Try out different pairs such as 5x and x/5; x^2 and sqrt(x); sin(x) and asin(x).

What do you notice?

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Freiza

Member

Registered: 2017-02-21

Posts: 6

Re: Inverse of function

Inverse of a function is the function which when combined to original function negates its operation.
f(x) o f(x)^-1 = f(x)^-1 o f(x) = identity operation (same as if no operation was performed) = x