#### Abstract

We obtain the classification of exact solutions, including soliton, rational, and elliptic solutions, to the one-dimensional general improved Camassa Holm KP equation and KdV equation by the complete discrimination system for polynomial method. In discussion, we propose a more general trial equation method for nonlinear partial differential equations with generalized evolution.

#### 1. Introduction

To construct exact solutions to nonlinear partial differential equations, some important methods have been defined such as Hirota method, tanh-coth method, the exponential function method, -expansion method, the trial equation method, [1–15]. There are a lot of nonlinear evolution equations that are integrated using the various mathematical methods. Soliton solutions, compactons, singular solitons, and other solutions have been found by using these approaches. These types of solutions are very important and appear in various areas of applied mathematics.

In Section 2, we give a new trial equation method for nonlinear evolution equations with higher-order nonlinearity. In Section 3, as applications, we obtain some exact solutions to two nonlinear partial diffeential equations such as the one-dimensional general improved Camassa Holm KP equation [16]: the dimensionless form of the generalized KdV equation [17]: In discussion, we propose a more general trial equation method.

#### 2. The Extended Trial Equation Method

*Step 1. * For a given nonlinear partial differential equation,
take the general wave transformation:
where and . Substituting (2.2) into (2.1) yields a nonlinear ordinary differential equation:

*Step 2. * Take the finite series and trial equation as follows:
where
Using (2.4) and (2.5), we can write
where and are polynomials. Substituting these relations into (2.3) yields an equation of polynomial of :
According to the balance principle, we can find a relation of , , and . We can compute some values of , , and .

*Step 3. *Let the coefficients of all be zero will yield an algebraic equations system:
Solving this system, we will determine the values of , , and .

*Step 4. * Reduce (2.5) to the elementary integral form:
Using a complete discrimination system for polynomial to classify the roots of , we solve (2.9) and obtain the exact solutions to (2.3). Furthermore, we can write the exact traveling wave solutions to (2.1), respectively.

#### 3. Applications

*Example 3.1 (Application to the Camassa Holm KP equation). *In order to look for travelling wave solutions of (1.1), we make the transformation , where and are arbitrary constants. Then, integrating this equation with respect to twice and setting the integration constant to zero, we obtain
We use the following transformation:
Equation (3.1) turns into the equation
Substituting (2.6) into (3.3) and using balance principle yield
After this solution procedure, we obtain the results as follows.

*Case 1. *If we take , , and , then
where , . Respectively, solving the algebraic equation system (2.8) yields
where . Substituting these results into (2.5) and (2.9), we have

where denotes by , and . Integrating (3.7), we obtain the solutions to the (1.1) as follows:
where
Also , , and are the roots of the polynomial equation
Substituting the solutions (3.8)–(3.10) into (2.4) and (3.2), we have
where denote by .

If we take and , then the solutions (3.15) can reduce to rational function solution:
1-soliton solution:
and singular soliton solution:
where , , , , and . Here, and are the amplitudes of the solitons, while is the velocity and is the inverse width of the solitons. Thus, we can say that the solitons exist for .

*Case 2. *If we take , and , then
where , . Respectively, solving the algebraic equation system (2.8) yields as follows.*Subcase 2.1*. It holds that
where . Substituting these results into (2.5) and (2.9), we get
Integrating (3.21), we obtain the solutions to (1.1) as follows:
where
Also , , , and are the roots of the polynomial equation:
Substituting the solutions (3.22)–(3.25) into (2.4) and (3.2), we have
where denotes by .

For simplicity, we can write the solutions (3.30) as follows:
*Subcase 2.2.* It holds that
where . Substituting these results into (2.5) and (2.9), we get
Integrating (3.33), we obtain the solutions to the (1.1) as follows.

If we denote
where , , then we can write complete discrimination system of as follows:
Correspondingly, there are the following two cases to be discussed.(1) If then we haveTherefore, the solution is given by

where
(2) If , then we have . From here, the solutions can be found as

For simplicity, we can write (3.40) as follows:

*Example 3.2 (Application to the generalized KdV equation). *Using a complex variation defined as , we can convert (1.2) into ordinary different equation, which reads
where the prime denotes the derivative with respect to . Integrating (3.42), and setting the constant of integration to be zero, we obtain
By the using of the transformation , (3.43) reduces to
Substituting (2.6) into (3.44) and using balance principle yield
If we take , , and , then
where , . Respectively, solving the algebraic equation system (2.8) yields
where denotes by and denote by . Substituting these results into (2.5) and (2.9), we can write
where denotes by . Integrating (3.48), we obtain the solutions to (1.2) as follows:
where
Also , , , and are the roots of the polynomial equation:
Substituting the solutions (3.49)–(3.52) into (2.4) and (3.2), we find
where denotes by .

If we take and , then the solutions (3.57) can reduce to rational function solutions:
traveling wave solutions:
and soliton solution:
where , , , , and . Here, is the amplitude of the soliton, while is the velocity and is the inverse width of the soliton. Thus, we can say that the solitons exist for .

#### 4. Discussion

Thus we give a more general extended trial equation method for nonlinear partial differential equations as follows.

*Step 1. *The extended trial equation (2.4) can be reduced to the following more general form:
where
Here, , , , and are the constants to be determined.

*Step 2. * Taking trial equations (4.1) and (4.2), we derive the following equations:
and other derivation terms such as , and so on.

*Step 3. * Substituting , and other derivation terms into (2.3) yields the following equation:
According to the balance principle, we can determine a relation of , , and .

*Step 4. * Letting the coefficients of all be zero will yield an algebraic equations system . Solving this equations system, we will determine the values ; ; , and .

*Step 5. * Substituting the results obtained in Step 4 into (4.2) and integrating equation (4.2), we can find the exact solutions of (2.1).

#### 5. Conclusions and Remarks

In this study, we proposed a new trial equation method and used it to obtain some soliton and elliptic function solutions to the Camassa Holm KP equation and the one-dimensional general improved KdV equation. Otherwise, we discussed a more general trial equation method. We think that the proposed method can also be applied to other nonlinear differential equations with nonlinear evolution.

Also, the convergence analysis of obtained elliptic solutions is given as follows: where Especially, , we have where . Taking the value , we have . Therefore, if we take in (3.13), in (3.28) and (3.55), in (3.38), for each , then we have By the using radius of convergence of power series: where . We have the radius of convergence of power series . We can say that power series converges for each , diverges for each . Consequently, the inequalities in (3.11), (3.26)–(3.53), and (3.38) are obtained by using , respectively.

#### Acknowledgment

The research has been supported by the Scientific and Technological Research Council of Turkey (TUBITAK) and Yozgat University Foundation.