[School shit] I get a little annoyed at textbook chapters that essentially say "So all the stuff you learned in the last section? Exactly all that but in a broader scope lol"
Like, in this math book it essentially says for a second order differential equation, the solution is y_1+y_2, and then the next section says "BTW for an n-th order differential equation the solution is y_1+y_2+...+y_n"