a) Sắp xếp: $\frac{-25}{19}$; $\frac{-13}{19}$; $\frac{9}{19}$; $\frac{14}{19}$; $\frac{20}{19}$; $\frac{30}{19}$ $\frac{42}{19}$
b) Có:
1/3 = 30/90
1/5 = 18/90
-2/15 = -12/90
1/6 = 15/90
-2/-5 = 2/5 = 36/90
-1/10 = -9/90
4/15 = 24/90
Vì: $\frac{-12}{90}$ < $\frac{9}{90}$ < $\frac{15}{90}$ < $\frac{18}{90}$ < $\frac{24}{90}$ < $\frac{30}{90}$ < $\frac{36}{90}$
Vậy sắp xếp: $\frac{-2}{15}$; $\frac{-1}{10}$; $\frac{1}{6}$; $\frac{1}{5}$; $\frac{4}{15}$; $\frac{1}{3}$; $\frac{-2}{-5}$
