So sánh phân số 5/11 và 3/21

e) $1-\frac{11}{12}=\frac{1}{12};1-\frac{12}{13}=\frac{1}{13}$

$\frac{1}{12}>\frac{1}{13}nên\frac{-11}{12}>\frac{-12}{13}$

g) - 3/2 < 0 và 5/6 > 0

=> - 3/2 < 5/6

h) $1-\frac{4}{5}=\frac{1}{5};1-\frac{6}{7}=\frac{1}{7}$

=> $\frac{1}{5}>\frac{1}{7}nên\frac{4}{5}<\frac{6}{7}$

a)

$\frac{3}{21}=\frac{1}{7}$

$1-\frac{5}{11}=\frac{6}{11}$

$1-\frac{1}{7}=\frac{6}{7}$

Ta có: $\frac{6}{11}<\frac{6}{7}nên\frac{5}{11}>\frac{3}{21}$

b) $\frac{-3}{5}<1;\frac{5}{3}>1$

=> $\frac{-3}{5}<\frac{5}{3}$

c) 5/4 >1

4/5 <1

=> 4/5 < 5/4

d) $\frac{-2}{11}<0$

$\frac{-3}{-4}=\frac{3}{4}>0$

=> $\frac{-2}{11}<\frac{-3}{-4}$