The general method of variation of parameters allows for solution ofsolving an inhomogeneous linear equation
:<math>Lx(t)=F(t)</math>
by interpretingmeans of considering the second-order linear differential operator ''L'' asto be the net force, so thatthus the total impulse imparted to a solution between time ''s'' and ''s''+''ds'' is ''F''(''s'')''ds''. Denote by <math>x_s </math> the solution of the homogeneous initial value problem