>>13848368Not him.
You know how to derive right ?
I'm pretty bad at latex, so bear with me and a shitty text.
You have
(d/dx)[(du/dx)v - u(dv/dx)] with u=psy* et v=psy, okay ?
You call linearity, then you derive two products, at the end you have four terms and two of them annul each other, and you have the result of before.
The first product:
(d/dx)[(du/dx)v] = (d/dx)(du/dx)v+(du/dx)(dv/dx)
The second one:
(d/dx)[u(dv/dx)] = (du/dx)(dv/dx)+u(d/dx)(dv/dx)
Now the first one minus the second one, and it's good (and yes it it -, you put + in your image)
