Investigation of the Class of the Rational Difference Equations ()
1. Introduction
The objective of this work is to investigate the asymptotic behavior of the solutions of the following difference equation
(1)
where
and
and the initial conditions
and
are arbitrary positive real numbers.
In recent years, there are a great interest in studying the rational difference equations. These equations describe real life situations in queuing theory, stochastic time series, combinatorial analysis, electrical network, number theory, genetics in biology, psychology, probability theory, statistical problems, economics, etc. The study of rational difference equations of high order (greater than one) is a big challenge. However, there have not been any effective general methods to deal with the global behavior of rational difference equations of order greater than one. Therefore, the study of such equations is so interesting. There has been a lot of work concerning the global asymptotic of solutions of rational difference equations [1] - [21] .
In fact, there has been a lot of interest in studying the behavior of the nonlinear difference equation of the form
(2)
For multiple delay and order, see [3] [18] [19] [20] and their references for more results of this equation. In Theorems 4.7.1-4.7.5 in [12] , Kulenovic investigated the asymptotic behavior of the solutions of the equation
(3)
Metwally et al. in [14] established a global convergence result and then apply it to show that under appropriate hypotheses every positive solution of the difference equation
where
for
. In [8] , Elsayed studied the periodicity, the boundedness, and the global stability of the positive solution of the difference equation
where the parameters
and
are positive real numbers and the initial conditions
are positive real numbers. Recently, Moaaz et al. [15] investigated some qualitative behavior of the following nonlinear difference equations
where the initial conditions
such that
are arbitrary real numbers and
and
are positive constants.
In this paper, in section 2, we state the sufficient condition for the asymptotic stability of Equation (1). Next, in section 3, we study the existence of periodic solutions of Equation (1). Finally, we study the boundedness nature of the solutions of Equation (1). Some numerical examples will be given to explicate our results.
During this study, we will need to many of the basic concepts. Before anything, the concept of equilibrium point is essential in the study of the dynamics of any physical system. A point
in the domain of the function
is called an equilibrium point of the equation
(4)
if
is a fixed point of
[
]. For a stability of equilibrium point, equilibrium point
of Equation (4) is said to be locally stable if for all
there exists
such that, if
for
with
. As well,
is said to be locally asymptotically stable if it is locally stable and there exists
such that, if
for
with
, then
. Also,
is said to be a global attractor if for every
for
, we have
. On the other hand,
is said to be unstable if it is not locally stable.
Finally, Equation (4) is called permanent and bounded if there exists numbers m and M with
such that for any initial conditions
for
there exists a positive integer N which depends on these initial conditions such that
for all
.
The linearized equation of Equation (1) about the equilibrium point
is
(5)
where
Theorem 1.1 [12] Assume that
for
. Then
(6)
is a sufficient condition for the asymptotic stability of Equation(1).
2. The Stability of Solutions
The positive equilibrium point of Equation (1) is given by
Now, we define a function
such that
Therefore, we find
(7)
(8)
(9)
and
(10)
Theorem 2.1. Assume that
be a
equilibrium point of Equation (1). If
where
and
, then
is local stable.
Proof. From (7) to (10), we get
and
Thus, the linearized equation of (1), is
From Theorem 1.1, we have that Equation (1) is locally stable if
and hence,
Then, we find
This completes the proof of Theorem 2.1.,
Example 2.1. Figure 1 shows that Equation (1) has local stable solutions if
,
,
,
,
,
and
.
Theorem 2.2. If
and
, then the equilibrium point
![]()
Figure 1. The stable solution corresponding to difference Equation (1).
Equation (1) is global attractor.
Proof. We consider the following function
(11)
Note that
non-decreasing for
and non-increasing for
. Let
a solution of the system
From (11), we have
and
Thus, we get
(12)
(13)
By subtracting (12) and (13), we have
Since
, we get
This completes the proof of this Theorem.,
3. Periodic Solution of Period Two
In this section, we investigate the existence of periodic solutions of Equation (1).
Theorem 3.1. Assume that
and
. Equation (1) has positive prime period-two solutions if
(14)
Proof. Suppose that there exists a prime period-two solution
of Equation (1). We will prove that condition (14) holds. We see from Equation (1) that if
and
, then
,
and so,
Thus, we have
(15)
and
(16)
By subtracting (15) and (16), we have
then, we find
(17)
By combining (15) and (16), we have
and so,
Since,
, we obtain
(18)
Now,it is clear from (17) and (18) that
and
are both two positive distinct roots of the quadratic equation
(19)
Hence, we obtain
which is equivalent to
This completes the proof of Theorem 3.1.,
Example 3.1. Consider Equation (1) with
,
,
,
and
. By Theorem 3.1, Equation (1) has prime period two solution (see Figure 2).
Example 3.2. Consider Equation (1) with
,
![]()
Figure 2. Prime period two solution of Equation (1).
![]()
Figure 3. Prime period two corresponding to differences Equation (1).
,
,
and
. By Theorem 3.1, Equation (1) has prime period two solution (see Figure 3).
4. Boundedness of the Solutions
In this section, we study the characteristic task of boundedness of the positive solutions of Equation (1).
Theorem 4.1. Every solution of (1) is bounded and persists.
Proof. From Equation (1), we have
then,
Hence, the proof is completed.,
Conclusion 1. This work is concerned with studying a dynamics and behavior of solutions of a new class of difference Equation (1). Our results extend and generalize to previous studies, for example, Equation (2) (if
) and Equation (3) (if
). Furthermore, we obtain the following results:
- The
equilibrium point
of equation (1) is local stable if
, where
and
. Also, if
and
, then
is global attractor.
- Equation (1) has a prime period-two solutions if
,
and
.
- Every solution of (1) is bounded and persists.
Acknowledgements
The authors are grateful to the editors and anonymous referees for a very thorough reading of the manuscript and for pointing out several inaccuracies.