Analysis of Mathematical Answers for Postgraduate Entrance Examination
G(h)=af(h)+bf(2h)-f(0), 0=lim g(h)=af(0)+bf(0)-f(0), so a+b- 1=0. 0 = lim g(h)/h = lim[af(h)+BF(2h)-f(0)/h = lim af(h)-f(0)/h+lim BF(2h)-f(0)/h = af '(0)+2bf '(。 The solution is a=2 and b=- 1.