# Help with reversing a function

1. Sep 21, 2008

### Trekky0623

I need to know how to start this.

Basically, I'm trying to isolate x on one side, so that I can input f(x) and solve for x, instead of the other way around.

Image: http://img146.imageshack.us/img146/8869/tempng8.png [Broken]

Last edited by a moderator: May 3, 2017
2. Sep 22, 2008

### mrandersdk

don't think that is possible

3. Sep 22, 2008

### Tac-Tics

Why would you ever want to invert such a useless function?

If it's homework and you're having trouble solving for x in terms of f(x), then there's a good chance the function is not one-to-one and thus has no inverse. The way you would prove this, though, is to find two values, x and y, such that f(x) = f(y). Alternatively, if you can plot the graph of the function, you can use a horizontal line test to see if it's one-to-one. If you can find a horizontal line that passes through two distinct points on the graph, then you can't invert it.

4. Sep 22, 2008

### CRGreathouse

Alternatively, if you just want the answer for yourself, you should consider numerical methods instead of analytic solutions.