ODE Exam! A simple ODE...please help!!! I've got a midterm exam later this morning on ODEs. I know how to solve second-order and higher ODEs with constant coefficients, but what about variable coefficients?? Can someone please walk me step-by-step through the solving of: y'' + A(x)y' + B(x)y = f(x), where ' indicates a derivative with respect to x. I really need to know this before the exam (I'll study for it myself too of course, but it would be really helpful if someone also explained it to me.). Thank you very much in advance for taking the trouble to help!