On a General Mittag-Leffler Theorem

We present a formal demonstration of a new theorem involving a three-parameter Mittag-Leffler function. As a by product, we recover some known results and we discuss a corollary which appear in a natural way. As an application we obtain the solution of the fractional differential equation associated with a $RLC$ electrical circuit in a closed form, involving the two-parameter Mittag-Leffler function.