i basically dont know how to do pde's, so i'm learning it from scratch today for my test which is tomorrow (which is in 24hrs from now, for those who dont live in australia), and notes/the internet arent nearly as good as explaining things as people are. so how would i go by starting these questions? any tips? for the second one (Q4), i know that method of separation of variables basically involves putting all the x's on one side and the y's on the other side. i dont understand how to find the boundaries, or what is insulated. i think it has something to do with those u(L,y)=0 etc constraints, which i'll look up. some guidance on how to start these questions please? as with my other threads, i'll post up my working out as i attempt these questions, to see how i'm going. thanks.