SOME RESULTS ON JACK’S LEMMA FOR ANALYTIC FUNCTIONS

In this paper, an upper bound will be found for the second coefficient in the Taylor expansion of the analytical function $pinsert ignore into journalissuearticles values(z);$ using the Jack lemma. Also, the modulus of the angular derivative of the $I_{f}insert ignore into journalissuearticles values(z);=\\frac{zp^{\\prime }insert ignore into journalissuearticles values(z);}{pinsert ignore into journalissuearticles values(z);}$ function on the unit disc will be estimated from below.