%J Journal of King Saud University - Science %A O. Said Solaiman %A S.A. Abdul Karim %A I. Hashim %L scholars11301 %I Elsevier B.V. %P 1499-1504 %X Starting by King's method, we propose a modified families of fourth- and eighth-order of convergence iterative methods for nonlinear equations. The fourth-order method requires at each iteration three function evaluations, while the eighth-order methods both need four function evaluations. The proposed methods are derivative-free. Based on the conjecture of Kung and Traub, the new methods attain the optimality with efficiency index 1.587 for the fourth-order method and 1.68 for the eighth-order methods. The convergence analyses of the methods are given, and comparisons with some well-known schemes having identical order of convergence demonstrate the efficiency of the present techniques. © 2018 The Authors %R 10.1016/j.jksus.2018.12.001 %N 4 %V 31 %T Optimal fourth- and eighth-order of convergence derivative-free modifications of King's method %O cited By 14 %D 2019