摘要:In this paper, we give an elementary proof that the real roots nonexistence of nonlinear equation such as: xn+yn+zn=n,where n =1,2,3,(x,y,z)∈ℝ by contradiction. Thus, when n takes all positive integers between 4 and 1981, the value of function f= xn+yn+znbased on the exact solution of the above equations is still real. Finally, numerical experiments presents a set of approximate numerical solutions by using standard genetic algorithm(SGA), adaptive particle swarm optimization algorithm(APSO) and artificial fish swarm algorithm(AFSA).