The tangent, represented by the graph of the function y=f(x), at the point with abscissa x=1 form an angle of π/6, at the point x=2 form an angle of π/3 and at the point x=3 form an angle of π/4. Then, find the value of, ∫13f′(x)f′′(x)dx+∫23f′′(x)dx.