# Thread: solve equation for x with lnx and x

1. ## solve equation for x with lnx and x

Hi, is it possible to solve the equation

y = alnx + bx + c?

I made it myself as it seems to best model something, and want a computer program i'm writing to be able to calculate x. Is this actually possible?

James

2. Originally Posted by jsab500
Hi, is it possible to solve the equation

y = alnx + bx + c?

I made it myself as it seems to best model something, and want a computer program i'm writing to be able to calculate x. Is this actually possible?

James
Do you want to solve for x in terms of y?

An exact solution will require using the Lambert W-function.

3. Yes in terms of y.

How would i go about doing that?

Thanks

4. Originally Posted by jsab500
Yes in terms of y.

How would i go about doing that?

Thanks
Are you familiar with the Lambert W-function?

What's wrong with using a numerical procedure to get an approximate value of x for a given value of y .....?

5. nothing's wrong with it, but if there was a way to just get x = whatever, it would be significantly simpler. I'll have a look at that Lambert-W function.

Thanks a lot