Solutions formulas for some general systems of difference equations

WOS:000741090800004In this paper, we give explicit formulas of the solutions of the two general systems of difference equations x(n+1 )= f(-1) (ag(y(n)) + bf (x(n-1)) + cg(y(n-2)) + df (x(n-3))) , y(n+1)= g(-1) (af (x(n)) + b(g)(y(n-1)) + cf (x(n-2)) + dg(y(n-3))) , and x(n+1) = f(-1) (a+b/g(y(n)) + c/ g(y(n))f(x(n-1)) + d/g(y(n))f(x(n-1))g(y(n-2))), y(n+1) = g(-1) (a+b/f(x(n)) + c/ f(x(n))g(y(n-1)) + d/f(x(n))g(y(n-1))f(x(n-2))), where n is an element of N-0, f, g : D -> R are "1 - 1" continuous functions on D subset of R, the initial values x(-i), y(-i), i = 0,1,2,3 are arbitrary real numbers in D and the parameters a, b, c and d are arbitrary real numbers. Our results considerably extend some existing results in the literature