Hi I'll be taking intro to diff eq this coming semester, and the course requires the Boyce and DiPrima Elementary Diff eq with boundary problems 9th edition. (https://www.amazon.com/Elementary-D...&sr=8-3&keywords=differential+equations+boyce) The 9th edition seems to be very expensive. The professor says that I need to use the 8th edition. However, I've found that with most math classes I've taken (which isn't a lot, just Calc II, Calc III, and Linear algebra), I just used the previous version. The homework problem numbers were out of the order and graphics were a bit different, but I didn't learn any less than anyone using the recommended current version. Also, it's been over a semester since calc III and linear algebra, so I'll try to cram in some reviews before the fall semester starts. What are some concepts from calc III and lin alg that I really need to have down before I tackle diff eq? Thanks!