show that [x,f(p_x)] = i [itex]\hbar[/itex] d/d(p_x) f(p_x)
x is the position operator in the x direction, p_x is the momentum operator; i [itex]\hbar[/itex]
The Attempt at a Solution
I'm stuck. maybe chain rule for d/dx and d/d(p_x)...? But I don't see how I'd do it...