1. The problem statement, all variables and given/known data 2. Relevant equations uv - integral of vdu 3. The attempt at a solution They don't seem to be using the integration by parts formula here. I don't understand why why they don't have a value for what z equals. dz = eu. well, what does z equal. I would think it would be the same thing. Next I don't anywhere where they're using the uv - integral of vdu formula. very bizarre.