From the numerical solutions in Tables 1,2, it can be seen that the exact solution (a a 20, respectively, is quite close to the approximate solution when a 0.95, a 1.95. Also, it is observed that the values of the approximate solution at different a's has the same behavior as those obtained using the exact solution, for which a l,a 2. This shows the approximate solution is efficiency. In the theory of fractional calculus, it is obvious that when the fractional derivative a(m 1 as m) tends to positive integer m, then the approximate solution continuously tends to the exact solution of the problem with derivative m 1,m 2. A closer look at the values in Tables 1 and 2, we observe that our approach do have this characteristic.