Can I thoroughly self teach myself maths with books and the internet? [closed]

I would say it is possible. A good teacher is is irreplaceable and can make a world of a difference in your education. But, truth to be told, most of the courses, at least in my experience, are not vastly different from writing the content of a set of lectures notes on a blackboard. I am not trying to be denigratory, and such courses still provide much value. In particular

1) The selection of material is appropriate. This is non-trivial: of course if you don't know the subject you don't know what to study. Furthermore, the typical book covers more material than the typical course, i.e. too much for a first go.

2) A lecturer may give a more "user friendly" treatment by giving more details of proofs/calculations or by working out a higher number of examples.

3) Exam/intermediate homework set a threshold for the minimum you should take out of the course.

But these points can be met even when self-studying. In the same order my advice would be:

1) Have a syllabus /set of lectures from a good university course so to know what is important and what may be skipped.

2) Get a book which is friendly and suited for self-study and which presents many worked out examples. Stay well clear of anything known to be concise/terse/foundational of which has similar words in the title. For a specific subject you can look at the threads here or open a new one in which you make clear your requirements.

3) Do not get too self-indulgent. Make sure that you can do (a reasonable number of) the exercises in your book. Even better, university exam sheets of past years are often available on the net, make sure that you can "pass" those.

So, it takes a bit more effort than following a university course but I think that it is doable. It won't be as good as what you get from the best courses/lecturers, but if done properly it is similar to what you would get out of an average course.

Internet makes things different, and I think something like math.stackexchange can be precious: for example if you have solved an exercise or proved something, it may be worth to post it here asking not only if your solution is correct, which maybe you know already, but if there are better ways of doing it and if you are learning how to apply the theory you have studied rather than using ad hoc methods (nothing wrong in finding non-standard solutions to a problem, but part of the point is to learn the machinery so that you can apply it those time that you cannot think of a clever trick).

Best of luck!