Section 2.6

[Itzal]

For questions 2 what does the last line of the given equations mean? The part is $u|_{x=+0}=\alpha u|_{x=-0}$  and $u_x|_{x=+0}=\beta u_x|_{x=-0}$. I don't know what this means or how to solve it with those parameters.

[Victor Ivrii]

Since $u$ is defined for $x<0$ and for $x>0$, you calculate limits from the left ($u|_{x=-0}$) and from the right ($u|_{x=+0}$). This is a standard notation