Question

Hi everyone! Can someone explain to me how you know when using the method of undetermined coefficients is applicable instead of using variation of parameters? Don't always know which is best and it seems like when I choose to do undetermined coefficients, I always have a gazillion terms and it was a bad choice. Thanks! :o)

Answer 1

I think I got it...
If g(x) is a constant, polynomial function, exponential function e^alphax, sinx, cosx, or finite sums or products of the sum, then you can use the method of undetermined coefficients.

So x^2(lnx) is logarithmic so you can't use it.