Yet another generation of students in ODE classes is forced to buy an exorbitantly priced new edition of the Boyce and DiPrima ODE text. Thank you for this wonderful and barely expanded ninth edition. Sample problem: 2.3.21 Assume that the conditions are as in problem 20 except that there is a force due to air resistance of |v|/30, where the velocity v is measured in m/s. Gee, I didn't know forces could be measured in m/s. Maybe they meant "proportional to." All I'm saying is... ninth edition... If you want to include the latest technology, publish a new textbook about the application of new technology to these problems. Don't give us a ninth edition of an old book with the same number of errors as the first and then, oh yeah, some flashy pictures and some neat problems you can do with CAS. I just know some student is going to write F_r=|v|/30 and things will just get more annoying from there.