Question

How can I get rid of C and D from [(aC+bD)^2]/[(bC+aD)^2]?

Answer 1

I tried to factor out by multiplying the fraction by (a/b)^2 and then divide by (b/a)^2 yet it seems to be impossible.

Answer 2

what's the original question you were given "vebatim"?

Answer 3

It's actually a physics question.
When the Schrodinger equation is satisfied by solutions of the form
u(x) = Aexp(ikx) + Bexp(-ikx) for x <= 0
u(x) = Cexp(iqx) + Dexp(-iqx) for x > 0,
Shouw that the reflection coefficient is given by
[(k-q) / (k+q)]^2.
I probably got the boundary conditions wrong.