Cetin, ErbilTopal, F. Serap2019-10-272019-10-2720160354-51800354-5180https://doi.org/10.2298/FIL1609551Chttps://hdl.handle.net/11454/53198Let T subset of R be a periodic time scale in shifts delta(+/-) with period P is an element of [t(0),infinity)(T). In this paper we consider the nonlinear functional dynamic equation of the form x(del)(t) = a(t)x(t) - lambda b(t)f(x(h(t))), t is an element of T. By using the Krasnoselskii, Avery-Henderson and Leggett-Williams fixed point theorems, we present different sufficient conditions for the nonexistence and existence of at least one, two or three positive periodic solutions in shifts delta(+/-) of the above problem on time scales. We extend and unify periodic differential, difference, h-difference and q-difference equations and more by a new periodicity concept on time scales.en10.2298/FIL1609551Cinfo:eu-repo/semantics/closedAccessperiodic time scaleperiodic solutionshift operatortime scaleArticle30925512571WOS:000393211000019Q2