ناجى صالح ابكر خلاف2022-05-192022-05-191135https://drepo.sdl.edu.sa/handle/20.500.14154/10227The thesis dealt with error estimates of approximate solutions in analytical for, thereby providing a measures of acceptences and effectiveness of the approximate method used. In general a differential equation is an equaltion containing derivatives. Any non-derivative relation between the variables of a differential equation which satistifies the equation is a solution of it.ar-SAThesis