1. The problem statement, all variables and given/known data What is the expectation value of <p*x> aka the momentum times the position operator, for a particle in a box. 2. Relevant equations Psi(x) = root(2/l) sin (n∏x/l) P= -ih(bar)d/dx X=x 3. The attempt at a solution All integrals are from 0 to L I'm typing this on a playbook so I won't show all my steps. -2ih/l ∫sin(n∏x/l)d/dx(xsin(nx/l) Which I got to be : sinx(sinx) + xcosx. My teacher however never gave us the integral of xcosx from 0 to l. So how can I solve this?