where a ≥ 1, b, λ > 0, p > 1 are constants, 1 p < α ≤ 1, 0 < γ < 1, ∈ C([0, 1]) and f ∈ C 1 ([0, T] × R, R). Under appropriate assumptions on the function f, we employ variational methods to show the existence and multiplicity of positive solutions of the above problem with respect to the parameter λ.