# (Methods)Parameters v Undetermined Coefficients

Well if you can guess the particular integral of a Diff eq'n then method of undetermined coefficients will work and the pi's you can usually guess are usually $e^{ax},sinax,cosax,sinax+cosax,etc.$. But if you have tanx or $\frac{1}{1+x}$ then you'll need to use variation of parameters to solve.