In this paper, we study an element which is both group invertible and Moore Penrose to be EP, partial isometry strongly EP by discussing the existence of solutions in a definite set some given constructive equations. Mainly, let ? R# R+. Then firstly show that REP if only Equation : axa+ + a+ax = 2x has at least one solution ?a {a, a#, a+, (a#)+, (a+)+}. Next, RSEP Equation: ?a. Finally, RPI ay...