Document Type: Research Paper
Department of Mathematics, Semnan University, P.O.Box. 35195-363, Semnan, Iran.
Mathematics, College of Engineering & Science Victoria University, PO Box 14428, Melbourne City, MC 8001, Australia. Urladdr: http://rgmia.org/dragomir.
Using the notion of eta-convex functions as generalization of convex functions, we estimate the difference between the middle and right terms in Hermite-Hadamard-Fejer inequality for differentiable mappings. Also as an application we give an error estimate for midpoint formula.