How do I find the inverse?

**Henryt999** · February 16th 2010, 08:24 AM

Problem is find the inverse of $f(x) = x^2-2x+4$

**Plato** · February 16th 2010, 08:30 AM

Originally Posted by Henryt999

Problem is find the inverse of $f(x) = x^2-2x+4$

The short answer is: you can't.
There must be some restrictions. What are they?

**Henryt999** · February 16th 2010, 10:11 AM

Originally Posted by Plato

The short answer is: you can't.
There must be some restrictions. What are they?

Ops, sorry it said: $f:[1,\infty)\rightarrow R, f(x) = x^2 -2x +4$

**icemanfan** · February 16th 2010, 10:16 AM

Set $x = y^2 - 2y + 4$

and solve for y.

**Henryt999** · February 16th 2010, 10:22 AM

Originally Posted by icemanfan

Set $x = y^2 - 2y + 4$

and solve for y.

Yes, thanks, that I understand I get
$x-4 = y(y-2)$
And now what?

**icemanfan** · February 16th 2010, 10:26 AM

Originally Posted by Henryt999

Yes, thanks, that I understand I get
$x-4 = y(y-2)$
And now what?

Try this:

$x = y^2 - 2y + 4$

$x = y^2 - 2y + 1 + 3$

$x = (y - 1)^2 + 3$

etc.

Thread: How do I find the inverse?