Derivative of a complex conjugate?

[xago]

Homework Statement

[PLAIN]http://img823.imageshack.us/img823/4500/85131172.png

Homework Equations

Derivations and substitutions.

The Attempt at a Solution

Basically it seems like a very simple problem to me however I can't seem to get the right answer. First I just assumed that the c.c. (complex conjugate) was just a constant thus:

$$\Psi$$'(x) = Cke^ikx
$$\Psi$$''(x) = Ck²e^ikx

But substituting that equation into the original DE gives:

Ck²e^ikx = Ck²e^ikx + k²(c.c)

obviously I'm missing something.

edit: maybe I read the question wrong could c.c. mean Ce^-ikx ?

 

[Dick]

Yes, the complex conjugate of exp(ikx) is exp(-ikx). And don't forget the c.c. of C is C^*. And d/dx(exp(ikx)) isn't k*exp(ikx) either, it's ik*exp(ikx).

 

[xago]

Ok, I understand now. Also thanks for pointing out my derivative mistake!