# Inverse function

• Oct 4th 2012, 06:47 PM
Chipset3600
Inverse function
Hi MHF, knowing that the quadratic function does not admit inverse, and that $\left | X\right | = \sqrt[2]{x^{^2}}$ a modular function have inverse? if yes, how can i find for example y= |x+2|-|3x+2|.
• Oct 4th 2012, 07:13 PM
Prove It
Re: Inverse function
Quote:

Originally Posted by Chipset3600
Hi MHF, knowing that the quadratic function does not admit inverse, and that $\left | X\right | = \sqrt[2]{x^{^2}}$ a modular function have inverse? if yes, how can i find for example y= |x+2|-|3x+2|.

Functions can only have inverses if they are one-to-one on their domain. It's pretty obvious that the example you gave is not one-to-one.
• Oct 4th 2012, 07:20 PM
Chipset3600
Re: Inverse function
Quote:

Originally Posted by Prove It
Functions can only have inverses if they are one-to-one on their domain. It's pretty obvious that the example you gave is not one-to-one.

But how can i see if the domain is one to one?
So assuming it to be y = | x |?
• Oct 4th 2012, 09:52 PM
Prove It
Re: Inverse function
Quote:

Originally Posted by Chipset3600
But how can i see if the domain is one to one?
So assuming it to be y = | x |?

Have you ever heard of the horizontal line test?
• Oct 5th 2012, 03:45 AM
Chipset3600
Re: Inverse function
Quote:

Originally Posted by Prove It
Have you ever heard of the horizontal line test?

that when I draw a horizontal line can only intercept function in only 1 point.
So the modular function it will never be one to one?
• Oct 5th 2012, 08:40 AM
HallsofIvy
Re: Inverse function
What is |2|? What is |-2|?

A function is either one-to-one or it is not. I don't know what you mean by "never be". You don't think it is sometimes one-to-one and sometimes not?
• Oct 5th 2012, 08:43 AM
Chipset3600
Re: Inverse function
|2|=|-2|=2... The doubt is If there is any modular function that admits inverse?