[notyourloops]

> There's no answers because the author gives thanks to a grad course in evidenced based teaching where he claims the only way to really know something and remember it is to figure it out for yourself. Math stackexchange can help too.

This is a cop out; of course to really know something and remember you have to figure it out for yourself. But answers allow you to check whether your work was right, and if not, allow you the opportunity to debug your work.

My best performance came in organic chemistry, where I looked for question banks (with answer keys) and solved problems extensively, perhaps bordering on obsessively. If I hadn't an indicator that my final result was wrong, I would have missed out on many learning opportunities, and objectively my performance would have been worse. In general, I have found this strategy to enable me to be an exceptional student.

If you don't benefit from an answer key, you're probably lazy and undisciplined. Alternatively, you have too much time on your hands, opting to rigorously confirm that each and every answer is correct.

In short, by not providing an answer key, you are denying the disciplined student the opportunity to efficiently learn.

[mindcrime]

In short, by not providing an answer key, you are denying the disciplined student the opportunity to efficiently learn.

I agree with you 100%. But let me add this: in most cases, if you're studying with a book that doesn't have an answer key, you can supplement that text with exercises taken from somewhere else. For example, lots of course websites around the 'net post previous years exams / homework with answers. There are also books like Schaum's 3,000 Solved Problems in Calculus[1], The Humongous Book of Calculus Problems[2], 3,000 Solved Problems in Linear Algebra[3], etc.

Also, with books that are used as textbooks, and that provide an answer key but only to instructors... if you aren't averse to violating copyright and using certain pirate websites, those "instructor only" answer keys can often be found.

[1]: https://www.amazon.com/Schaums-Solved-Problems-Calculus-Outl...

[2]: https://www.amazon.com/Humongous-Book-Calculus-Problems-Book...

[3]: https://www.amazon.com/000-Solved-Problems-Linear-Algebra/dp...

[hackermailman]

He has extensive posts on his reasons, but it's also used for a course so only letting other professors have the answers to allow reuse of exercises is another reason. Those Art of Problem solving olympiad books don't have answers either with authors claiming same reasoning and in their defense I did learn a lot figuring it out myself. Personally I too like gratification of solving something then seeing the answers and finding a different and almost always more elegant/clear proof to compare to mine.