Representation of solutions of a solvable nonlinear difference equation of second order

• Published in: Electronic journal of qualitative theory of differential equations 2018-01, Vol.2018 (95), p.1-18
• Main Authors: Stević, Stevo, Iričanin, Bratislav, Kosmala, Witold, Šmarda, Zdeněk
• Format: Article
• Language: English
• Subjects: linear difference equation; nonlinear second-order difference equation; representation of solutions; solvable difference equation
• ISSN: 1417-3875; 1417-3875
• DOI: 10.14232/ejqtde.2018.1.95

We present a representation of well-defined solutions to the following nonlinear second-order difference equation $$x_{n+1}=a+\frac{b}{x_n}+\frac{c}{x_nx_{n-1}},\quad n\in\mathbb{N}_0,$$ where parameters $a, b, c$, and initial values $x_{-1}$ and $x_0$ are complex numbers such that $c\ne0$, in terms of the parameters, initial values, and a special solution to a third-order homogeneous linear difference equation with constant coefficients associated to the nonlinear difference equation, generalizing a recent result in the literature, completing the proof therein by using an essentially constructive method, and giving some theoretical explanations related to the method for solving the difference equation. We also give a more concrete representation of the solutions to the nonlinear difference equation by calculating the special solution to the third-order homogeneous linear difference equation in terms of the zeros of the characteristic polynomial associated to the linear difference equation.