I'm using the method of undetermined coefficients to find a particular solution of:
$$y''+y'=xe^{-x}$$
Ostensibly, it seems that $y_p$ should take the form of $(Ax + B)e^{-x}$
At least that's the form that I think I've been taught. Problem is that it just doesn't work out for me. I get a value for A, but not for B... Am I choosing an incorrect yp form?