1. The problem statement, all variables and given/known data write the solutions to the S.E in regions x<o and x between o and a 2. Relevant equations I believe psi(x)= e^ikx+Re^-ikx in x<0 and psi(x)=Ae^iqx+Be^-iqx for x b/w o and a. 3. The attempt at a solution My question is, since there is complete reflection occuring at x=a, can A=B in region x b/w 0 and a? If so, there will be destructive interference in the region, giving R=1, which is what we are asked to prove in the question. Is this approach of equating coefficients of wave traveling in +-x directions in this region applicable?