Existence and approximation of solutions for a class of boundary value problems on time scales of the type − [p(t)y∆(t)]∇ + q(t)y(t) = f(t, y(t)), t ∈ [a, b]T, c1y(ρ(a))− c2y(ρ(a)) = 0, d1y(b) + d2y(b) = 0, is established. For the existence theory, we develop the method of upper and lower solutions. To approximate the solution, we develop the generalized method of quasilinearization. We show th...