As far as I know, Y(X) cannot be expressed in elementary functions in general.

Results 1 to 5 of 5

- June 14th 2013, 01:23 AM #1

- Joined
- Jun 2013
- From
- UK
- Posts
- 2

- June 14th 2013, 01:38 AM #2

- Joined
- Oct 2009
- Posts
- 5,573
- Thanks
- 789

- June 14th 2013, 02:13 AM #3

- Joined
- Feb 2013
- From
- Saudi Arabia
- Posts
- 445
- Thanks
- 86

- June 14th 2013, 02:21 AM #4

- Joined
- Jun 2013
- From
- UK
- Posts
- 2

- June 14th 2013, 07:21 AM #5

- Joined
- Apr 2005
- Posts
- 18,073
- Thanks
- 2390

## Re: help for my son

so the equation can be written as or . Let Z= -Yln(X). Then and so the equation becomes and then .

Now apply "Lambert's W function" to both sides. "Lambert's W function" is**defined**as the inverse function to so . Of course, "Lambert's W function" is NOT an "elementary function" so emakarov is completely correct.