Abstract
The Exp-function method has been widely used to solve different kinds of nonlinear partial differential equations. These nonlinear partial differential equations are transformed first into nonlinear ordinary differential equations and then the ansatz of the Exp-function method: u=∑n=−cpanexp(nη)∑m=−dqbmexp(mη) is applied to obtain the solution. However, a part of the solution using this method is to construct the relations between c, p, d and q by balancing the highest order linear term with the highest order nonlinear term. It is proved in the present paper that c=d and p=q are the only relations that can be obtained by applying this method to any nonlinear ordinary differential equation. Therefore, the additional calculations of balancing the highest order linear term with the highest order nonlinear term are not longer required in future. Hence, the method becomes more straightforward.