solve, this method allows the calculation of the coefficients of the general solution of the inhomogeneous equation, and thus the complete general solution of the inhomogeneous equation can be determined. Note that and are each determined only up to an arbitrary additive constant (the constant of integration). Adding a constant to or does not change the value of because the extra term is just a linear combination of u1 and u2, which is a solution of by definition. Notes References See also Reduction of order Alekseev–Gröbner formula, a generalization of the variation of constants formula. External links Online Notes / Proof by Paul Dawkins, Lamar University. PlanetMath page. A NOTE ON LAGRANGE’S METHOD OF VARIATION OF PARAMETERS Ordinary differential equations