Bài 1. So sánh A và B biết rằng :
a) A = \(\frac{10^{15}+1}{10^{16}+1}\); B = \(\frac{10^{16}+1}{10^{17}+1}\)
b) A = \(\frac{3}{8^3}\)+\(\frac{7}{8^4}\); B = \(\frac{7}{8^3}\)+\(\frac{3}{8^4}\)
c) A = \(\frac{1}{11}\)+\(\frac{1}{12}\)+\(\frac{1}{13}\)+ ... +\(\frac{1}{19}\)+\(\frac{1}{20}\); B = \(\frac{1}{2}\)