cho A=40+\(\frac{8}{3}+\frac{7}{8^2}\frac{5}{8^3}\frac{32}{8^5}vàB=\frac{24}{8^2}+40+\frac{5}{8^2}+\frac{40}{8^2}\frac{5}{8^4}.\)

tính nhanh

a) \(\frac{-3}{7}+\frac{5}{13}+\frac{3}{7}\)

b)\(\frac{-5}{21}+\frac{-2}{21}+\frac{8}{24}\)

c) \(\frac{-5}{11}+\left(\frac{-6}{11}+2\right)\)

d)\(\left(\frac{-1}{32}+\frac{1}{2}\right)+\frac{-15}{32}\)

so sánh các phân số sau

a) \(\frac{-219}{220}và\frac{215}{216}\)

b) \(\frac{-1999}{2000}và\frac{-2000}{2001}\)

c) \(\frac{403}{407}và\frac{813}{817}\)

d) \(\frac{-251}{138}và\frac{-317}{171}\)