“…The main results are proved in Section 2, which is organized as follows: In the subsection 2.1 we consider the case when τ (t) > t and in the subsection 2.2, we consider the case when τ (t) ≤ t. The results in this paper are different from the results established in [21] even in the case when τ (t) = t and can be applied to the equation (1.1) when 0 < γ < 1 and τ (t) > t. The results improve the results established in [1,14,15,19,29,22], in the sense that the results do not require the conditions (1.8), (1.11), (1.13) and r ∆ (t) ≥ 0. The results also can applied on any time scale not only on discrete time scales when µ(t) = 0, which is the case considered in [8].…”