Affiliation: | a Department of Mathematics and Statistics, Bowen University, P.M.B. 284, Iwo, Osun State, Nigeria b College of Natural and Applied Sciences, Department of Physical Sciences, Bells University of Technology, P.M.B 1015, Ota, Ogun State, Nigeria c Department of Mathematics, University of Ibadan, Ibadan, Nigeria d Department of Mathematics, Obafemi Awolowo University, Ile-Ife, Nigeria |