Lie symmetries and conserved quantities of first order Lagrange systems

In this paper, a system of first order ordinary differential equations is e xpressed in the form df first order Lagrange equations. The determining equ ations of Lie symmetries are established by the invariance of the ordinary differential equations under the infinitesimal transformations. The conditi on under which a Lie symmetry can lead to a conserved quantity is obtained and the form of the conserved quantities is given.