Integrating Factor, how do you get this?
As I said, they didn't "drop" mu, they solved for it!
If
[tex]\frac{du}{dx}= F(x)u[/tex]
then
[tex]\frac{du}{u}= F(x)dx[/tex]
and, integrating both sides,
[tex]ln(u)= \int F(x)dx[/tex]
Now take the exponential of both sides.
