Fekete-Szego Inequalities for Some Certain Subclass of Analytic Functions Defined with Ruscheweyh Derivative Operator

In our present investigation, we introduce and study some new subclasses of analytic functions associated with Ruscheweyh differential operator D-r. We obtain a Fekete-Szego inequality for certain normalized analytic function defined on the open unit disk for which [(D(r)l)'(z)](theta) (z(D(r)l)'(z)/(D(r)l)(z))(1-theta) (sic) e(z) (0 <= theta <= 1) lies in a starlike region with respect to 1 and symmetric with respect to the real axis. As a special case of this result, the Fekete-Szego inequality for a class of functions defined through Poisson distribution series is obtained.