# Need help on this differential equation

1. Sep 17, 2011

### cpamieta

1. The problem statement, all variables and given/known data
Well this is a physics problem, need find the potential function

2. Relevant equations
$\Psi$ =Axe-kx A and k are constants
I need to find d2 $\Psi$/dx2

3. The attempt at a solution
I thought u would just take the derivative two times
but just d$\Psi$/dx = Ae-kx-kAxe-kx
Would i do something like this?
http://tutorial.math.lamar.edu/Classes/DE/Linear.aspx
thanks

2. Sep 17, 2011

### vela

Staff Emeritus
What's the problem with just differentiating it again?

3. Sep 17, 2011

### cpamieta

i forgot how you do a differential equation, i have the solutions. I want to know how you do the dΨ/dx
i thought it would just be dΨ/dx= -A/ke-kx Its been a long summer lol

4. Sep 17, 2011

### vela

Staff Emeritus
You don't have a differential equation. You're simply differentiating a function twice.

For this particular function, you need to use the product rule and chain rule, and you need to know how to differentiate a polynomial and an exponential.

5. Sep 17, 2011

### cpamieta

o ok thxs the wolfan alpha thing said it was when i typed it in. It also gave somthing different