  We present a method for reducing the order of ordinary differential equations
satisfying a given scaling relation (Majorana scale-invariant equations). We
also develop a variant of this method, aimed to reduce the degree of
non-linearity of the lower-order equation. Some applications of these methods
are carried out and, in particular, we show that second-order Emden-Fowler
equations can be transformed into first-order Abel equations. The work
presented here is a generalization of a method used by Majorana in order to
solve the Thomas-Fermi equation.
