[RESOLVED] LogNormal function

I need your help guys.

How to solve these two equations for X and Y?

http://img224.imageshack.us/img224/3...rmal3gw.th.jpg

Thanks in advance.

The first equation:
G = e^{y + x2/2}
G = e^{(2y + x2)/2}
G² = e^{2y + x2}
Now compare this to Z:
Z² = e^{2y + x2} * (e^x2 - 1)
So:
Z² / G² = (e^x2 - 1)
Now you can solve this equation for x; y shouldn't be a problem after that.

After viewing your solution it seems surprisingly simple! You have been of great help. Thank you so much.