“…where ∆ denotes the forward difference operator defined by ∆u(k) = u(k + 1) − u(k), ∆ i+1 u(k) = ∆(∆ i u(k)), f, g : [2, T ] Z × R −→ R are two continuous functions, and α, β, λ, µ are real parameters and satisfy : λ > 0, µ > 0 and 1 + (T − 1).T α − + T.(T − 1) 3 .β − > 0, (1.2) where : α − = min(α, 0) and β − = min(β, 0).…”