Which is the best book to prepare for the SAT subject test, Maths 2 that has helped improving the scores? Thank you for your answer.
That question has been asked here many times - you can search if you want to see the details.
I asked/researched the same in the Spring for my D, and ended up with Barron’s and the official College Board guide. Be aware that the Barron’s tests are typically 40-60 points harder than the actual test. They’re good practice, but can be worrisome if you’re not aware of that fact.
Barron’s can be a bit short on detail in some area - a few Khan videos helped in areas that she hadn’t learned in pre-calc (vectors, matrices, parametrics).
Princeton was helpful